- Aug 2021
Beatrice Webb, the famous sociologist and political activist, reported in 1926: "'Every one agrees nowadays', observe the most noted French writers on the study of history, 'that it is advisable to collect materials on separate cards or slips of paper. . . . The advantages of this artifice are obvious; the detachability of the slips enables us to group them at will in a host of different combinations; if necessary, to change their places; it is easy to bring texts of the same kind together, and to incorporate additions, as they are acquired, in the interior of the groups to which they belong.'" 
Webb 1926, p. 363. The number of scholars who have used the index card method is legion, especially in sociology and anthropology, but also in many other subjects. Claude Lévy-Strauss learned their use from Marcel Mauss and others, Roland Barthes used them, Charles Sanders Peirce relied on them, and William Van Orman Quine wrote his lectures on them, etc.
In writing my dissertation and working on my first book, I used an index card system, characterized by the "one fact, one card" maxim, made popular by Beatrice Webb. 
I've not come across Beatrice Webb before, but I'm curious to see what her system looks like based on this statement.
From the footnotes:
She observed in the appendix to her My Apprenticeship of 1926, called The Art of Note-Taking: "It is difficult to persuade the accomplished graduate of Oxford or Cambridge that an indispensable instrument in the technique of sociological enquiry - seeing that without it any of the methods of acquiring facts can seldom be used effectively - is the making of notes" Webb, Beatrice (1926) My Apprenticeship (London: Longmans, Green, and Co.), pp. 426-7.