Delicate and precise, neatly arranged in alphabetical lemmas. I stumbled across the manuscripts in the Special Collections of the Leiden University Library, where they were listed in the inventory as ‘Adversaria of mixed content’. Without further explanation, except that their author was Jan Wagenaar. This eighteenth-century author was a household name in his time, writing about history, theology, and politics. Now here I was, looking at the notes he had used to write all those books, sermons, and pamphlets.The four leather-bound volumes contained pages and pages of lemmas on a variety of topics, from ‘concubines’ to ‘thatched roofs in the cities of Holland’. The lemmas included excerpts from a variety of texts, including snippets in French, English and Hebrew. This was how Wagenaar tried to organise his information flows, subsequently using this information to produce new texts.

“Adversaria” was an actor’s term for reading notes, which highlighted the factthat reading notes stood in relationship to another text (without any connota-tion of that relationship being adversarial).45

Make fleeting notes. Always have something at hand to write withto capture every idea that pops into your mind.

He also jotted down, as Johannes Schmidt has found in his research, a few keywords along with the respective page num-bers (in early modern Europe, this excerpting system was called adversaria or lemmata).83

ike Jungius, Boyle made use of loose folio sheets that he called memorials or adversaria; yet he did not worry too much about a system of self-referential relationships that enabled intentional knowl-edge retrieval. When he realized that he was no longer able to get his bearings in an ocean of paper slips, he looked for a way out, testing several devices, such as colored strings or labels made of letters and numeral codes. Unfortunately, it was too late. As Richard Yeo clearly noted, ‘this failure to develop an effective indexing system resulted from years of trusting in memory in tandem with notes’.69

Definition of adversaria 1 : commentaries or notes (as on a text or document) 2 : a miscellaneous collection of notes, remarks, or selections : commonplace book

Francesco Sacchini recommends two notebooks inDeratione libros cum profectu legendi libellus(Wu ̈rzburg, 1614), chap. 13, p. 91: “Not unlike attentivemerchants . . . [who] keep two books, one small, the other large: the first you would calladversariaor a daybook(ephemerides),the second an account book(calendarium)and ledger(codex).”

acon favored the latter as “of far more profitW and use” Squotedin “tpW” pY ae‘TY

́hese notesW generally presented in the order of the text from whichthey were producedW are often called adversariaY

wn a looser sense the term is also used to designate notes of any kindW as in the tdvY shelfmark inthe qambridge ˆniversity zibrary reserved for books containing marginal annotationsi see ̧illiam vY `hermanW –ohn weem The Politics of Reading and Writing in the xnglish RenaissanceSomherstW ffassYW ]ggcTW ppY dc–ddY

Like so manynaturalists of the Enlightenment, he was familiar with a wide variety of textual techniques, manyof which were direct descendants of the compositional and pedagogical tools used to harness themnemonic utility of words inscribed on the clean spaces of erasable surfaces such as librellos dememoria and chalk boards, or upon more permanent forms of print such as commonplace books(adversaria), cabinet labels, marginaliaand printed books.