Warburg definitely read Bernheim's Lehrbuch!!! He excerpted it! Though based on the footnote in the text, it may appear that his quotation was from the 1908 edition of Bernheim.

Machine translation of the German:

Warburg assigned another piece of paper to these organicistic considerations about historical development, which follows a »hidden plan« (Menke-Glückert), on which he noted a passage from Ernst Bernheim’s Lehrbuch der Historischen Method in which Wilhelm Wundt is referred to, who explains, as Warburg excerpts, »that historical general processes are applications of general psychological principles, such as e.g. B. the reaction is an application of the principle of "contrast enhancement".

362 Z. 0 02/0 0 0411. Warburg zitier t Wundt, Logik. Eine Untersuchung der Principien der Erkenntnis und der Methode wissenschaf tlicher Forschung, Stuttgar t 1895, Bd. II/2, S. 413, aus Ernst Bernheim, Lehrbuch der Historischen Methode und der Geschichtsphilosophie. Mit Nachweis der wichtigsten Quellen und Hilfsmit tel zum Studium der Geschichte, Leipzig 1908, S. 60 f.

Link to: https://hypothes.is/a/Th2g4kVoEe6OSV9qNo31rQ

Steiner, Benjamin. “Aby Warburgs Zettelkasten Nr. 2 ‘Geschichtsauffassung.’” In Zettelkästen. Maschinen der Phantasie, edited by Heike Gfrereis and Ellen Strittmatter, 154–61. Marbacher Kataloge 66. Marbach am Neckar, 2013. https://www.academia.edu/8637204/Aby_Warburgs_Zettelkasten_Nr_2_Geschichtsauffassung_.

example photos of some of Aby Warburg's zettels, kasten, and a photo of his desk space at home with zettelkasten to one side.

machine translation:

Anyone who follows Warburg's list of notes is following his train of thought; from the banking system in Florence, medieval commercial society, the development of individuality, the restless professional work of the Calvinists and the reformed form of asceticism to Warburg's own origins in an old Jewish banking family. 378 The Zettelkasten is Warburg's Ariadne thread through his labyrinthine library and his labyrinthine thinking: from werewolf to history. A thought, an idea or a new concept does not emerge in a linear progression, but in a process of moving idea units and cross-references back and forth, which lasts until new interfaces and nodes have formed.

Karl Lamprecht was one of Warburg's first teachers in Bonn and Warburg had a section in his zettelkasten dedicated to him. While Warburg wasn't part of the broader public debate on Lamprecht's Methodenstreit (methodological dispute), his notes indicate that he took an active stance on thinking about it.

Consult footnote for more:

59 Vgl. Roger Chickering, »The Lamprecht Controversy«, in: Historiker- kontroversen, hrsg. von Hartmut Lehmann, Göttingen 20 0 0, S. 15 – 29

Aby Warburg's (1866-1929) zettelkasten had references to Ernst Bernheim (1850-1942). Likelihood of his having read Lehrbuch der historischen Methode (1889) as potential inspiration for his own zettelkasten?

When did Warburg start his zettelkasten?

According to Wikipedia, Warburg began his study of art history, history and archaeology in Bonn in 1886. He finished his thesis in 1892, so he may have had access to Bernheim's work on historical method. I'll note that Bernheim taught history at the University of Göttingen and at the University of Bonn after 1875, so they may have overlapped and even known each other. We'll need more direct evidence to establish this connection and a specific passing of zettelkasten tradition, though it may well have been in the "air" at that time.

Warburg had an incongruous seeming section of his zettelkasten relating to the idea of "Werewolf" which was tied into a variety of other ideas.

Steiner considers the order and position of Warburg's notes within his boxes and assumes that they were not meant to be static, but would have been easily reordered, revised, and changed according to Warburg's needs. He describes them as a hodgepodge with a liquid mobility which are granted some form of stability afforded by the internal tabs.

Warburgs slips hold not only his own thoughts along with collections of keywords, but excerpts from books, critical remarks, and diagrams that provide overviews of ideas and their connections.

Warburg's zettelkasten does not appear to be a simple bibliographic classification system according to Steiner. He indicates that the books in Warburg's library are arranged according to Warburg's idea of »guten Nachbarschaft« or "good neighborliness" whereby they followed his subjective interests an ordering that is reflected in the labels of his note boxes and various tabs which subsection notes within them.

Warburg had note cases especially designed for travelling with him around Europe as he did research and lectured.

Warburg's zettelkasten consisted of more than 100 boxes decorated in colorful Japanese paper.

https://www.reddit.com/r/Zettelkasten/comments/13cqnsk/do_you_suffer_from_verkn%C3%BCpfungszwang_the/

I recently watched the documentary Aby Warburg: Metamorphosis and Memory (Wechsler, 2016) via Kanopy (for free using my local library’s gateway) and thought that others here interested in the ideas of memory in culture, history, and art history may appreciate it. While a broad biography of a seminal figure in the development of art history in the early 20th century, there are some interesting bits relating to art and memory as well as a mention of Frances A. Yates whose research on memory was influenced by Warburg’s library.

Of specific "note” is the fact that Aby Warburg (1866-1929) had a significant zettelkasten-based note taking practice and portions of his collection (both written as well as images) are featured within the hour long documentary. You'll see it in the opening scenes in the background during many of the interviews, but there's also a portion featured at the 30 minute mark which looks at a few of his zettels. Like several other zettelkasten practitioners he had a significant zettelkasten practice but did not publish much, but did lecture quite a lot and had outsized influence both during his life as well as posthumously and his zettelkasten and research remain as an archive for scholars who still study and extend his work.

Sadly, I'm unable to catch any screenshots from the film due to technical glitches, but if folks can figure out how to pull some out, I'd appreciate them.

Aby Warburg's extant zettelkasten at the Warburg Institute's Archive consists of ninety-six surviving boxes (of 104 or possibly more) which contain between 200-800 individually numbered index cards. Dividers and envelopes are used within the boxes to separate the cards into thematic sections.

The digitized version is transcribed in the original German and is not available translated into English (at least as of 2023). The digitized version maintains the structure of the dividers and consists of only about 3,200 items. It can be searched at https://wi-calm.sas.ac.uk/CalmView/Aboutcatalogue.aspx. As examples one can find the record for box 4a on "the Renaissance" at https://wi-calm.sas.ac.uk/CalmView/Record.aspx?src=CalmView.Catalog&id=WIA+III.2.1.+ZK%2f4a&pos=1 and the physical divider inside box 4a for "Jakob Burkhardt" with subsections listed at https://wi-calm.sas.ac.uk/CalmView/Record.aspx?src=CalmView.Catalog&id=WIA+III.2.1.+ZK%2f4a%2f2&pos=1

The Warburg Institute archive had this sample photo of some of his decorative/colorful boxes:

Has anyone visited the Warburg archive in London before?

syndication link

The searchable digital archive for Aby Warburg's zettelkasten at The Warburg Institute: https://wi-calm.sas.ac.uk/CalmView/Default.aspx

https://wi-calm.sas.ac.uk/CalmView/Record.aspx?src=CalmView.Catalog&id=WIA+III.2.1.+ZK%2f4a&pos=1

Example of record for ZK box 4a on the Renaissance.

https://wi-calm.sas.ac.uk/CalmView/Record.aspx?src=CalmView.Catalog&id=WIA+III.2.1.+ZK%2f4a%2f2&pos=1

An example of a digital record of a physical divider in Aby Warburg's zettelkasten for Jakob Burkhardt with subsections listed.

Ref No: WIA III.2.1. ZK/4a/2<br /> Title: Jakob Burkhardt Briefe<br /> Physical Description: Divider<br /> Contents: Subsections: 1rst level: Vorträg Burckhardt 1927 Sommersemester [appr. 56 items, numbered and unnumbered]; 2nd level: Burckhardt an Nietzsche; 3rd level: Brief Nietzsches an Burckhardt 6 Januar 1889. 2nd level: Jakob Burckhardt und die nordische Kunst Conversations Lexikon, Burckhardt Festwesen, zu Rougemont Cicerone, Wanderer in der Schweiz, Hedlinger, Hedlinger.

https://wi-calm.sas.ac.uk/CalmView/Aboutcatalogue.aspx

Aby Warburg's extant zettelkasten at the Warburg Institute's Archive consists of ninety-six surviving boxes which contain between 200-800 individually numbered index cards. Dividers and envelopes are used within the boxes to separate the cards into thematic sections.

The digitized version is transcribed in the original German and is not available translated into English (at least as of 2023). The digitized version maintains the structure of the dividers and consists of only about 3,200 items.

A full catalog of Aby Warburg's 104 index card boxes (reference: WIA III.2.1.ZK) are available online by way of The Warburg Institute's online database at http://wi-calm.sas.ac.uk/calmview/. They are catalogued at the file level.

via https://warburg.sas.ac.uk/archive/archive-online-catalogues