In 1983, at the dawn of the personal computer age, Apple Inc. in promotional film entitled "Lisa Soul Of A New Machine" touted their new computer, a 16-bit dual disk drive "personal office system", as something that would do away with "the cluttered desk, index cards, file folders, the in-out basket, [and] the calculator." (00:01)

Some of these things moved to the realm of the computer including the messy desk(top) now giving people two messy desks, a real one and a virtual one. The database-like structure of the card index also moved over, but the subjective index and its search power were substituted for a lower level concordance search.

30 years on, for most people, the value of the database idea behind the humble "index card" has long since disappeared and so it seems here as if it's "just" another piece of cluttery paper.

Appreciate the rosy framing of the juxtaposition of "past" and "future" jumping over the idea of the here and now which includes the thing they're selling, the Lisa computer. They're selling the idealized and unclear future even though it's really just today.

this was never produced?

Elaine Svenonius in Facet Definition: a Case Study https://web.archive.org/web/20220803153450id_/https://www.nomos-elibrary.de/10.5771/0943-7444-1978-3-134.pdf comes to a similar conclusion

Only two volumes of the three were ever produced as far as I can tell.

Variations of card index systems were published in booklet form by filing cabinet manufacturers as a means of selling not only their cabinets, but their systems for using them was common in the early 1900s. Examples of magazine advertisements in System Magazine back this up. It is also specifically highlighted in a review of J. Kaiser's book "The Card System at the Office" from Ironmonger (1909-10-03) which appreciates a more fully fleshed out version of a card index system in book form without mention of specific manufacturing firms.

Kaiser, J. Systematic Indexing. The Card System Series 2. London: Sir Isaac Pitman & Sons, Ltd., 1911. http://archive.org/details/systematicindexi00kaisuoft.

Annotation URL: urn:x-pdf:2acc267d4cbe455af640e4a707a84692

Alternate: https://jonudell.info/h/facet/?user=chrisaldrich&max=100&exactTagSearch=true&expanded=true&url=urn%3Ax-pdf%3A2acc267d4cbe455af640e4a707a84692

See alternate version at: # or https://www.google.com/books/edition/Systematic_Indexing/iwFDAAAAIAAJ?hl=en Google-Books-ID: iwFDAAAAIAAJ

(Switched for better OCR)

https://search.worldcat.org/title/20718283

J. Kaiser's The card system at the Office was translated to French in 1914 by G. et M. Ravisse, Paris.

Regular note taking practice will be the best indicator of when potential improvements are worthwhile. Though you may see someone else's advice, workflows, or potential improvements, they may be just as likely not to work for you and your particular needs. Adopting changes without thinking them through or even practicing them for a while are more likely to cause harm, regret, or additional work without any value added to the system.

examples of specific workflows within Kaiser's card system

This is a restatement that a particular system should be customized to its users.

There is potential that a system could be applied universally, but it requires a very large amount of data and metadata to suit the needs of a greater number of people and use cases. It also requires a reasonable amount of work in practical use to make it operate as expected.

The Mundaneum was likely close on paper and Google comes close to this, but still isn't perfect.

quote via ¶76 and 92

Devising Card Systems

Many modern-day note takers and knowledge workers might take solace in the broad advice provided by J. Kaiser in 1908. In describing some of the broad categories of uses of card index filing systems for business use he says that each entity "has its individual character and individual requirements, and its individual character" (ie, everyone is different and has different needs), therefore everyone "must devise [their] system in accordance with [their] own requirements" and should "be the best judge as to what these requirements are." He continues on in the rest of the book to outline a variety of suggestions and methods which one might use or adopt, but he doesn't dictate specific methods and leaves those decisions up to the end user.

When devising their own systems, one certainly ought to heed this advice when looking at a variety of alternative methods like Forte's P.A.R.A., Milo's LYT, or even in mimicking Luhmann's idiosyncratic Zettelkasten set up. Are these methods best for your particular use cases? Are they simple enough for what you want to do, or are they overly structured and complicated? The key is to be able to classify and file things quickly so that they can be easily accessed in the future, all the rest becomes additional details and overhead to support on an ongoing basis.

(¶76)

Julius Kaiser contemporaneously posits that mass manufacture and maximizing efficiency (greater output for minimum input) are the primary drivers of card index system use in the early 20th century. These also improve both precision and accuracy in handling information which allow for better company or factory operation, which would have been rising concerns for businesses and manufacturing operations at the rise of scientific management during the time period.

He notes the general equivalency of cards and papers in vertical files.

One of the primary affordances that individual atomic cards have is the ability to more easily re-arrange and reuse them for various purposes in comparison with larger sheets with greater amounts of data on them.

The nebulous, but colloquial "card system" was a common, but now lost moniker for the use of a card index in business settings in the early 1900s.

https://de.wikipedia.org/wiki/Lernkartei

https://betterhumans.pub/i-built-my-own-personal-productivity-system-around-a-3-x-5-index-card-147d7a8d83de

Melange of GTD, card index, and gamification....

Update 2024-01-04: I knew I had heard/seen this system before, but not delved into it deeply. I hadn't seen anyone either using it or refer to it by name in the wild until yesterday. All the prior mentions were people sharing the URLs as a thing rather than as something they used.

https://thetodaysystem.com/

The Today System:

A simple, yet scalable personal productivity system, centered around a single 3 x 5″ index card.

used by u/runslack

I accomplished a couple of other things on that first day back into reality. First, with an evil Grinch-like smile | uprooted every household management system | had ever tried, and tore up every single 3x5 card in them. Then one by one, | roasted and toasted them in the fireplace until they were gone, gone, gone. Next, with equally fiendish delight, | speared my $35 namebrand notebook organizer with a marshmallow fork, and | roasted it too. It melted into oblivion, all but it’s ugly metal spine. Next, | prayed for my attitude and for help. And finally, | marched myself into Wal-mart and bought my first clear plastic bin, a two pound sack of M&M's, and a loaf of white bread. For better or worse, we have been pretty happy campers at my house ever since. (p6)

• for: system justification theory, Kiffer Card, Kirk Hepburn

A 9 x 5" card that folds in three to make a 3 x 5" card for planning out one's entire week.

This is quite clever with respect the space of cards like Analog and 3x5 Life.

via: https://www.3x5life.com/collections/frontpage/products/3x5-life-system-with-mini-course

They apparently offer a mini course outlining the system.

One wonders how much "why" they offer?

https://www.3x5life.com/

Compare with other products in this category: - Analog (Jeff Sheldon productivity system) - Memindex - Bullet Journal - Frictionless Capture Cards - Pile of Index Cards

Following a pattern seen in many modern wooden recipe card boxes to hold the current recipe one is working on, Jeff Sheldon has cut a long thin slot into his card holder to allow one to stand up today's card in the front as a means of displaying and featuring what needs to get done.

https://www.kickstarter.com/projects/ugmonk/analog-the-simplest-productivity-system

Jeff Sheldon's Analog productivity system is a physical product consisting of a wooden tray, metal divider, 3 x 5" custom printed index cards (and refills), a felt carrier, and other accessories which functions as a minimalistic version of the old Memindex.

Luhmann mentions that he only wrote on one side so that he didn't need to physically remove notes from the box when searching it. There is a level of lost productivity if one needs to physically remove a card to read it and then replace it; this lost productivity is magnified if one uses their slip box regularly over the span of many years.

https://www.3m.co.uk/3M/en_GB/post-it-notes/ideas/articles/make-the-leap-from-to-do-to-done-with-the-scrum-methodology/

"The Scrum method" described here, similar to the Kanban method, the Memindex method, tickler systems, or other card index as productivity systems, seems to be a productized name for selling Post-it Notes.

Scrum method consists of a project broken down into "story" rows with "to do" items in columns which progress along to "in process", "to verify", and finally "done".

Other productized names (particular to the note taking space): Antinet zettelkasten, Linking Your Thinking, Second Brain, etc.

Wigent, William David, Burton David William Housel, and Edward Harry Gilman. Modern Filing and How to File: A Textbook on Office System. Rochester, N.Y.: Yawman & Erbe Mfg. Co., 1916. http://archive.org/details/modernfilingate02compgoog.

Interesting to see a passing mention of Hawk Sugano's Pile of Index Cards here in a note taking context rather than a productivity one.

The Great Vaccinator

https://waaa.wnyc.org/radiolab_podcast/radiolab_podcast20greatvaccinator.mp3/radiolab_podcast20greatvaccinator.mp3_ywr3ahjkcgo_7d3105f4ceea640a7c9df376fa60ffce_43057055.mp3?hash_redirect=1&x-total-bytes=43057055&x-ais-classified=streaming&listeningSessionID=0CD_382_72__176a88639f0d9f459a1123b260a07f59e7746372

Listened to on 2023-03-11

Much like Richard Feynman kept a list of his 12 favorite problems, Maurice Hilleman kept a running list of diseases for which he was working on developing vaccines to remedy.

General instructions for using a Memindex

HOW IT IS USED <br /> Things to be done today, jot on face card. Things to be done tomorrow or next Friday, jot on card for that day. Things to keep before you until done, jot on opposite front card. A matter for January 10th jot on a short card put under the band till you return to your desk, then file next to card for January 10th when it will come out and refresh your memory.

Things to be done when in New York or Chicago jot on card "N" or "C." The new address of Mr. Jones, under "J." Ideas on advertising jot on card tabbed "adv." Things for your clerk to do, on his card , etc., etc. Retire today's card tonight, carrying forward things not completed and put next card in the file in has proved that almost back of pocket case. The alphabet enables one to index all jottings for instant reference. This system is very comprehensive yet perfectly simple. You soon the learn to depend on it every hour of every day.

Within the general instructions in a 1904 Memindex advertisement (next to an ad for "Genuine Edison Incandescent Lamps") we see the general ideas of indexing things into the future and carrying undone tasks forward, just as is done in the bullet journal method.

Geyers Stationer. “Memindex Advertisement.” Geyer’s Stationer: Devoted to the Interests of the Stationery, Fancy Goods and Notion Trades, September 15, 1904. https://www.google.com/books/edition/Geyer_s_Stationer/L507AQAAMAAJ?hl=en&gbpv=0

Howard L. Wilson of Rochester, NY named his vest pocket card index system the Memindex.

Poem from the inside back cover of a 1913 Memindex Catalog:

JUST JOT IT DOWN.

If you’re going to meet a man<br /> Jot it down<br /> If you’ve got a little plan<br /> Jot it down<br /> If you never can remember<br /> Your requirements for September<br /> ’Till October or November<br /> Jot ’em down.

If you’ve got a note to pay<br /> Jot it down<br /> If its due the first of May<br /> Jot it down<br /> If collections are so slow<br /> That to meet the note you know<br /> You must dun old Richard Roe<br /> Jot it down

If you have a happy thought<br /> Jot it down<br /> If there’s something to be bought<br /> Jot it down<br /> Whether duty calls or pleasure<br /> If you’re busy or at leisure<br /> It will help you beyond measure<br /> Jot it down

If there’re facts that you’d retain<br /> Jot ’em down<br /> If you’ve got to meet a train<br /> Jot it down<br /> If at work or only play<br /> If at home or far away<br /> In the night or in the day<br /> Jot it down

c.1913 Wilson Memindex Desk Organzier Catalog Price List Booklet Rolodex Prequel

In a 1913 catalog for the Wilson Memindex, the company suggested putting to do items and one's schedule on one side of the card and potentially keeping one's accounts or a diary on the reverse side.

1930s Wilson Memindex Co Index Card Organizer Pre Rolodex Ad Price List Brochure

archived page: https://web.archive.org/web/20230310010450/https://www.ebay.com/itm/165910049390

Includes price lists

List of cards includes: - Dated tab cards for a year from any desired. - Blank tab cards for jottings arranged by subject. - These were sold in 1/2 or 1/3 cut formats - Pocket Alphabets for jottings arranged by letter. - Cash Account Cards [without tabs]. - Extra Record Cards for permanent memoranda. - Monthly Guides for quick reference to future dates. - Blank Guides for filing records by subject.. - Alphabet Guides for filing alphabetically.

Memindex sales brochures recommended the 3 x 5" cards (which had apparently been standardized by 1930 compared to the 5 1/2" width from earlier versions around 1906) because they could be used with other 3 x 5" index card systems.

In the 1930s Wilson Memindex Company sold more of their vest pocket sized 2 1/4 x 4 1/2" systems than 3 x 5" systems.

Some of the difference between the vest sized and regular sized systems choice was based on the size of the particular user's handwriting. It was recommended that those with larger handwriting use the larger cards.

By the 1930's at least the Memindex tag line "An Automatic Memory" was being used, which also gave an indication of the ubiquity of automatization of industrialized life.

The Memindex has proved its success in more than one hundred kinds of business. Highly recommended by men in executive positions, merchants, manufacturers, managers, .... etc.

Notice the gendering of users specifically as men here.

Features: - Sunday cards were sold separately and by my reading were full length tabs rather than 1/6 tabs like the other six days of the week - Lids were custom fit to the bases and needed to be ordered together - The Memindex Jr. held 400 cards versus the larger 9 inch standard trays which had space for 800 cards and block (presumably a block to hold them up or at an angle when partially empty).

The Memindex Jr., according to a price sheet in the 1930s, was used "extensively as an advertising gift".

The Memindex system had cards available in bundles of 100 that were labeled with the heading "Things to Keep in Sight".

Vintage Memindex Wilson Wood Box 1937-38 Diary Planner Date Keeper Ephemera

Includes particularly good image of the individual day cards:

Notice that the tabs are done as 1/6th as most of these systems were manufactured/sold with out including Sunday.

Getting Things Done with Index Cards<br /> by Jazz DiMauro

referenced in Lifehacker article as early as 2005

Note the use of envelopes for separation. Did this predate the Noguchi Filing System, inspired by it or wholly separate?

The Hipster PDA<br /> by Gina Trapani

And Mr. H. Beebe of Chicago, using but one drawer, says: "It has made me keep appointments and lay out my work to increase the things I can do in a day. "

Example of sales touting productivity in a filing system.

Note also the specific gendering of the clerk here in 1906.

Vintage 1900 Macey Card Business System Fred Macey Company Original Ad 1021 A2<br />

https://www.ebay.com/itm/275147213477

Copy in notes folder as backup

Copy in Notes folder.

https://www.ebay.com/itm/275144504113

As humans we're good at separating things based on categories. The Dewey Decimal System systematically separates mathematics and history into disparate locations, but your zettelkasten shouldn't force this by overthinking categories. Perhaps the overlap of math and history is exactly the interdisciplinary topic you're working toward? If this is the case, just put cards into the slip box closest to their nearest related intellectual neighbor—and by this I mean nearest related to you, not to Melvil Dewey or anyone else. Over time, through growth and branching, ideas will fill in the interstitial spaces and neighboring ideas will slowly percolate and intermix. Your interests will slowly emerge into various bunches of cards in your box. Things you may have thought were important can separate away and end up on sparse branches while other areas flourish.

If you make the (false) choice to separate math and history into different "sections" it will be much harder for them to grow and intertwine in an organic and truly disciplinary way. Universities have done this sort of separation for hundreds of years and as a result, their engineering faculty can be buildings or even entire campuses away from their medical faculty who now want to work together in new interdisciplinary ways. This creates a physical barrier to more efficient and productive innovation and creativity. It's your zettelkasten, so put those ideas right next to each other from the start so they can do the work of serendipity and surprise for you. Do not artificially separate your favorite ideas. Let them mix and mingle and see what comes out of them.

If you feel the need to categorize and separate them in such a surgical fashion, then let your index be the place where this happens. This is what indices are for! Put the locations into the index to create the semantic separation. Math related material gets indexed under "M" and history under "H". Now those ideas can be mixed up in your box, but they're still findable. DO NOT USE OR CONSIDER YOUR NUMBERS AS TOPICAL HEADINGS!!! Don't make the fatal mistake of thinking this. The numbers are just that, numbers. They are there solely for you to be able to easily find the geographic location of individual cards quickly or perhaps recreate an order if you remove and mix a bunch for fun or (heaven forfend) accidentally tip your box out onto the floor. Each part has of the system has its job: the numbers allow you to find things where you expect them to be and the index does the work of tracking and separating topics if you need that.

The broader zettelkasten, tools for thought, and creativity community does a terrible job of explaining the "why" portion of what is going on here with respect to Luhmann's set up. Your zettelkasten is a crucible of ideas placed in juxtaposition with each other. Traversing through them and allowing them to collide in interesting and random ways is part of what will create a pre-programmed serendipity, surprise, and combinatorial creativity for your ideas. They help you to become more fruitful, inventive, and creative.

Broadly the same thing is happening with respect to the structure of commonplace books. There one needs to do more work of randomly reading through and revisiting portions to cause the work or serendipity and admixture, but the end results are roughly the same. With the zettelkasten, it's a bit easier for your favorite ideas to accumulate into one place (or neighborhood) for easier growth because you can move them around and juxtapose them as you add them rather than traversing from page 57 in one notebook to page 532 in another.

If you use your numbers as topical or category headings you'll artificially create dreadful neighborhoods for your ideas to live in. You want a diversity of ideas mixing together to create new ideas. To get a sense of this visually, play the game Parable of the Polygons in which one categorizes and separates (or doesn't) triangles and squares. The game created by Vi Hart and Nicky Case based on the research of Thomas Schelling provides a solid example of the sort of statistical mechanics going on with ideas in your zettelkasten when they're categorized rigidly. If you rigidly categorize ideas and separate them, you'll drastically minimize the chance of creating the sort of useful serendipity of intermixed and innovative ideas.

It's much harder to know what happens when you mix anthropology with complexity theory if they're in separate parts of your mental library, but if those are the things that get you going, then definitely put them right next to each other in your slip box. See what happens. If they're interesting and useful, they've got explicit numerical locators and are cross referenced in your index, so they're unlikely to get lost. Be experimental occasionally. Don't put that card on Henry David Thoreau in the section on writers, nature, or Concord, Massachusetts if those aren't interesting to you. Besides everyone has already done that. Instead put him next to your work on innovation and pencils because it's much easier to become a writer, philosopher, and intellectual when your family's successful pencil manufacturing business can pay for you to attend Harvard and your house is always full of writing instruments from a young age. Now you've got something interesting and creative. (And if you must, you can always link the card numerically to the other transcendentalists across the way.)

In case they didn't hear it in the back, I'll shout it again: ACTIVELY WORK AGAINST YOUR NATURAL URGE TO USE YOUR ZETTELKASTEN NUMBERS AS TOPICAL HEADINGS!!!

Thoughts on Zettelkasten numbering systems

I've seen variations of the beginner Zettelkasten question:

"What happens when you want to add a new note between notes 1/1 and 1/1a?"

asked at least a dozen times in the Reddit fora related to note taking and zettelkasten, on zettelkasten.de, or in other places across the web.

Dense Sets

From a mathematical perspective, these numbering or alpha-numeric systems are, by both intent and design, underpinned by the mathematical idea of dense sets. In the areas of topology and real analysis, one considers a set dense when one can choose a point as close as one likes to any other point. For both library cataloging systems and numbering schemes for ideas in Zettelkasten this means that you can always juxtapose one topic or idea in between any other two.

Part of the beauty of Melvil Dewey's original Dewey Decimal System is that regardless of how many new topics and subtopics one wants to add to their system, one can always fit another new topic between existing ones ad infinitum.

Going back to the motivating question above, the equivalent question mathematically is "what number is between 0.11 and 0.111?" (Here we've converted the artificial "number" "a" to a 1 and removed the punctuation, which doesn't create any issues and may help clarify the orderings a bit.) The answer is that there is an infinite number of numbers between these!

This is much more explicit by writing these numbers as:<br /> 0.110<br /> 0.111

Naturally 0.1101 is between them (along with an infinity of others), so one could start here as a means of inserting ideas this way if they liked. One either needs to count up sequentially (0, 1, 2, 3, ...) or add additional place values.

Decimal numbering systems in practice

The problem most people face is that they're not thinking of these numbers as decimals, but as natural numbers or integers (or broadly numbers without any decimal portions). Though of course in the realm of real numbers, numbers above 0 are dense as well, but require the use of their decimal portions to remain so.

The tough question is: what sorts of semantic meanings one might attach to their adding of additional place values or their alphabetical characters? This meaning can vary from person to person and system to system, so I won't delve into it here.

One may find it useful to logically chunk these numbers into groups of three as is often done using commas, periods, slashes, dashes, spaces, or other punctuation. This doesn't need to mean anything in particular, but may help to make one's numbers more easily readable as well as usable for filing new ideas. Sometimes these indicators can be confusing in discussion, so if ever in doubt, simply remove them and the general principles mentioned here should still hold.

Depending on one's note taking system, however, when putting cards into some semblance of a logical sort-able order (perhaps within a folder for example), the system may choke on additional characters beyond the standard period to designate a decimal number. For example: within Obsidian, if you have a "zettelkasten" folder with lots of numbered and named files within it, you'll want to give each number the maximum number of decimal places so that when doing an alphabetic sort within the folder, all of the numbered ideas are properly sorted. As an example if you give one file the name "0.510 Mathematics", another "0.514 Topology" and a third "0.5141 Dense Sets" they may not sort properly unless you give the first two decimal expansions to the ten-thousands place at a minimum. If you changed them to "0.5100 Mathematics" and "0.5140 Topology, then you're in good shape and the folder will alphabetically sort as you'd expect. Similarly some systems may or may not do well with including alphabetic characters mixed in with numbers.

If using chunked groups of three numbers, one might consider using the number 0.110.001 as the next level of idea between them and then continuing from there. This may help to spread some of the ideas out as surely one may have yet another idea to wedge in between 0.110.000 and 0.110.001?

One can naturally choose almost any any (decimal) number, so long as it it somewhat "near" the original behind which one places it. By going out further in the decimal expansion, one can always place any idea between two others and know that there will be a number that it can be given that will "work".

Generally within numbers as we use them for mathematics, 0.100000001 is technically "closer" by distance measurement to 0.1 than 0.11, (and by quite a bit!) but somehow when using numbers for zettelkasten purposes, we tend to want to not consider them as decimals, as the Dewey Decimal System does. We also have the tendency to want to keep our numbers as short as possible when writing, so it seems more "natural" to follow 0.11 with 0.111, as it seems like we're "counting up" rather than "counting down".

Another subtlety that one sees in numbering systems is the proper or improper use of the whole numbers in front of the decimal portions. For example, in Niklas Luhmann's system, he has a section of cards that start with 3.XXXX which are close to a section numbered 35.YYYY. This may seem a bit confusing, but he's doing a bit of mental gymnastics to artificially keep his numbers smaller. What he really means is 3000.XXX and 3500.YYY respectively, he's just truncating the extra zeros. Alternately in a fully "decimal system" one would write these as 0.3000.XXXX and 0.3500.YYYY, where we've added additional periods to the numbers to make them easier to read. Using our original example in an analog system, the user may have been using foreshortened indicators for their system and by writing 1/1a, they may have really meant something of the form 001.001/00a, but were making the number shorter in a logical manner (at least to them).

The close observer may have seen Scott Scheper adopt the slightly longer numbers in the thousands (like 3500.YYYY) as a means of remedying some of the numbering confusion many have when looking at Luhmann's system.

Those who build their systems on top of existing ones like the Dewey Decimal Classification, or the Universal Decimal Classification may wish to keep those broad categories with three to four decimal places at the start and then add their own idea number underneath those levels.

As an example, we can use the numbering for Finsler geometry from the Dewey Decimal Classification wikipedia page shown as:

``` 500 Natural sciences and mathematics

510 Mathematics

    516 Geometry

        516.3 Analytic geometries

            516.37 Metric differential geometries

                516.375 Finsler geometry

```

So in our zettelkasten, we might add our first card on the topic of Finsler geometry as "516.375.001 Definition of Finsler geometry" and continue from there with some interesting theorems and proofs on those topics.

Of course, while this is something one can do doesn't mean that one should do it. Going too far down the rabbit holes of "official" forms of classification this way can be a massive time wasting exercise as in most private systems, you're never going to be comparing your individual ideas with the private zettelkasten of others and in practice the sort of standardizing work for classification this way is utterly useless. Beyond this, most personal zettelkasten are unique and idiosyncratic to the user, so for example, my math section labeled 510 may have a lot more overlap with history, anthropology, and sociology hiding within it compared with others who may have all of their mathematics hiding amidst their social sciences section starting with the number 300. One of the benefits of Luhmann's numbering scheme, at least for him, is that it allowed his system to be much more interdisciplinary than using a more complicated Dewey Decimal oriented system which may have dictated moving some of his systems theory work out of his politics area where it may have made more sense to him in addition to being more productive on a personal level.

Of course if you're using the older sort of commonplacing zettelkasten system that was widely in use before Luhmann's variation, then perhaps using a Dewey-based system may be helpful to you?

A Touch of History

As both a mathematician working in the early days of real analysis and a librarian, some of these loose ideas may have occurred tangentially to Gottfried Wilhelm Leibniz (1646 - 1716), though I'm currently unaware of any specific instances within his work. One must note, however, that some of the earliest work within library card catalogs as we know and use them today stemmed from 1770s Austria where governmental conscription needs overlapped with card cataloging systems (Krajewski, 2011). It's here that the beginnings of these sorts of numbering systems begin to come into use well before Melvil Dewey's later work which became much more broadly adopted.

The German "file number" (aktenzeichen) is a unique identification of a file, commonly used in their court system and predecessors as well as file numbers in public administration since at least 1934. We know Niklas Luhmann studied law at the University of Freiburg from 1946 to 1949, when he obtained a law degree, before beginning a career in Lüneburg's public administration where he stayed in civil service until 1962. Given this fact, it's very likely that Luhmann had in-depth experience with these sorts of file numbers as location identifiers for files and documents. As a result it's reasonably likely that a simplified version of these were at least part of the inspiration for his own numbering system. † ‡

Your own practice

At the end of the day, the numbering system you choose needs to work for you within the system you're using (analog, digital, other). I would generally recommend against using someone else's numbering system unless it completely makes sense to you and you're able to quickly and simply add cards to your system with out the extra work and cognitive dissonance about what number you should give it. The more you simplify these small things, the easier and happier you'll be with your set up in the end.

References

Krajewski, Markus. Paper Machines: About Cards & Catalogs, 1548-1929. Translated by Peter Krapp. History and Foundations of Information Science. MIT Press, 2011. https://mitpress.mit.edu/books/paper-machines.

Munkres, James R. Topology. 2nd ed. 1975. Reprint, Prentice-Hall, Inc., 1999.

https://lifehacker.com/the-pile-of-index-cards-system-efficiently-organizes-ta-1599093089

LifeHacker covers the Hawk Sugano's Pile of Index Cards method, which assuredly helped promote it to the GTD and productivity crowd.

One commenter notices the similarities to Ryan Holiday's system and ostensibly links to https://thoughtcatalog.com/ryan-holiday/2013/08/how-and-why-to-keep-a-commonplace-book/

Two others snarkily reference using such a system to "keep track of books in the library [,,,] Sort them out using decimal numbers on index cards in drawers or something..." and "I need to tell my friend Dewey about this! He would run with it." Obviously they see the intellectual precursors and cousins of the method, though they haven't looked at the specifics very carefully.

One should note that this may have been one of the first systems to mix information management/personal knowledge management with an explicit Getting Things Done set up. Surely there are hints of this in the commonplace book tradition, but are there any examples that go this far?

An example of a ticker file in the vein of getting things done (GTD) documented using index cards and a card file from 1917. Sounds very familiar to the Pile of Index Cards (PoIC) from the early 2000s.

Sutherland, Lois Gilbert. “The English Teacher’s Card File.” The English Journal 6, no. 2 (1917): 111–12. https://doi.org/10.2307/801508.

Lois Gilbert Sutherland suggests using a card index system for multiple uses in the classroom including notes, administration, and general productivity.

There are so many parallels from this to how people are using platforms like Obsidian, Roam Research, and Notion in 2022.

https://www.youtube.com/results?search_query=pile+of+index+card

Doesn't look like there's any of the "original" PoIC material on YouTube, but some examples of related practices to check into.

1. BNF, NAF 28630, ‘Grand fichier’, 3 January 1975.

Roland Barthes' biographer Tiphaine Samoyault quotes portions of what he calls Barthes' card index diary.

This can also be seen in the published cards which comprise Barthes' Mourning Diary about the period following his mother's death.

Are there other people who've used their card index as a diary the way that some use it for productivity?

syndication link

Dwyer, Edward J. “File Card Efficiency.” Journal of Reading 26, no. 2 (1982): 171–171.

Ease of use in writing and grading with short assignments by using 4 x 6" index cards in classrooms.

This sounds like some of the articles from 1912 and 1917 about efficiency of card indexes for teaching.

I'm reminded of some programmed learning texts that were card-based (or really strip-based since they were published in book form) in the 1960s and 1970s. Thse books had small strips with lessons or questions on the front with the answers on the reverse. One would read in strips through the book from front to back and then start the book all over again on page one on the second row of strips and so on.

Goutor defines self-help notes as notes which one would use to refresh their memory about what remains to be done or researched, problems that remain to be solved, or information which is needed to be researched or found. (p26) These are akin in some sense to what I call "open questions". He also indicates that these notes might be triggered by one's daily activities or occasional musings which relate to one's project but occur outside of its active pursuit. In this sense, they have a similar feel to the idea of Ahrens' fleeting notes, but in Goutor's practice they aren't defined as occurring while one is doing active reading or research.

He suggests that one keeps these notes in a separate area so that they might be systematically and regularly visited for review, further research, or answering as the opportunities to do so present themselves. Once the questions have been answered and appropriate notes updated or added, these self-help notes can be discarded.

While Heyde outlines using keywords/subject headings and dates on the bottom of cards with multiple copies using carbon paper, we're left with the question of where Luhmann pulled his particular non-topical ordering as well as his numbering scheme.

While it's highly likely that Luhmann would have been familiar with the German practice of Aktenzeichen ("file numbers") and may have gotten some interesting ideas about organization from the closing sections of the "Die Kartei" section 1.2 of the book, which discusses library organization and the Dewey Decimal system, we're still left with the bigger question of organization.

It's obvious that Luhmann didn't follow the heavy use of subject headings nor the advice about multiple copies of cards in various portions of an alphabetical index.

While the Dewey Decimal System set up described is indicative of some of the numbering practices, it doesn't get us the entirety of his numbering system and practice.

One need only take a look at the Inhalt (table of contents) of Heyde's book! The outline portion of the contents displays a very traditional branching tree structure of ideas. Further, the outline is very specifically and similarly numbered to that of Luhmann's zettelkasten. This structure and numbering system is highly suggestive of branching ideas where each branch builds on the ideas immediately above it or on the ideas at the next section above that level.

Just as one can add an infinite number of books into the Dewey Decimal system in a way that similar ideas are relatively close together to provide serendipity for both search and idea development, one can continue adding ideas to this branching structure so they're near their colleagues.

Thus it's highly possible that the confluence of descriptions with the book and the outline of the table of contents itself suggested a better method of note keeping to Luhmann. Doing this solves the issue of needing to create multiple copies of note cards as well as trying to find cards in various places throughout the overall collection, not to mention slimming down the collection immensely. Searching for and finding a place to put new cards ensures not only that one places one's ideas into a growing logical structure, but it also ensures that one doesn't duplicate information that may already exist within one's over-arching outline. From an indexing perspective, it also solves the problem of cross referencing information along the axes of the source author, source title, and a large variety of potential subject headings.

And of course if we add even a soupcon of domain expertise in systems theory to the mix...

While thinking about Aktenzeichen, keep in mind that it was used in German public administration since at least 1934, only a few years following Heyde's first edition, but would have been more heavily used by the late 1940's when Luhmann would have begun his law studies.

https://hypothes.is/a/CqGhGvchEey6heekrEJ9WA

When thinking about taking notes for creating output, one can follow one thought with another logically both within one's card index not only to write an actual paper, but the collection and development happens the same way one is filling in an invisible outline which builds itself over time.

Linking different ideas to other ideas separate from one chain of thought also provides the ability to create multiple of these invisible, but organically growing outlines.

Ryan Holiday notes the similarity of his method to that of the Dewey Decimal system and library card catalogs.