From A Place for Everything, by Judith Flanders (Basic Books, 2020), Kindle pp. 184-185:
The Abbé François Rozier (1734–1793), a botanist and friend of Jean-Jacques Rousseau, was commissioned by the Académie des Sciences in Paris to produce an index of its publications. Rozier did not think he was doing anything revolutionary; in fact, had he been asked, it is likely he would have described his method as traditional, even old-fashioned, following as it did Gesner’s description of how to create a bibliography. He organized his work, which he referred to in turn as an index, a dictionary, and a concordance—“the name doesn’t matter,” he wrote—in a patchwork of unwieldy systems that demanded substantial preliminary knowledge of anyone using it. He rejected pure alphabetical order in favor of keywords, although even then he indexed the members of the Académie chronologically by the date of their election to the society, with further subcategories based on their membership rank. To find, say, Leibniz in this work, the searcher needed to know the year the philosopher had joined the Académie; that, as a foreigner, he had been given only associate membership; and that he was indexed under the French variant of his name, Godefroy-Guillaume Leibnitz. Despite this, the material on which Rozier wrote out his old-fashioned catalog was one that looked forward—was, indeed, path-breaking: “Playing cards are best for creating these tables,” he decreed.
Rozier’s choice of medium for his unwieldy jottings was a stroke of organizational genius. Eighteenth-century playing cards were printed with the suits and values on one side, as ours are today, but the reverse was left blank …. Nor did eighteenth-century cards have the shiny high finish of modern ones. Playing cards were also easily available, and inexpensive; they were designed for constant handling, and were therefore more durable than paper; they did not stick together, as pieces of paper often do, so they were easier to flick through; and they were a standard size, making storage simpler.
As with the librarians of the Josephinian, Rozier’s expectation was that these cards would serve as an interim measure to help him order his material before the finished indexes were bound and published, and in his case this is exactly what happened. But when, two decades later, the Bastille was stormed and the French Revolution overturned the ancien régime, information concerning a defunct royal society was of little moment to a new republic. Nonetheless, Rozier’s choice of writing medium was adopted wholesale. A year after the nationalization of the clerical libraries, the government planned a nationwide survey of its new possessions, hoping to amalgamate all holdings into a single central catalog of all books in all libraries throughout France.