See here. I am rather doubtful about this history. Thus, it is not really true that Linné (Linnaeus) "invented" the index card. For one thing, he used paper slips, and for another, playing cards and paper slips were used already for the purpose of cataloging and taking notes long before him. What about Aldrovandi or Gessner as the "inventors" of the index card in the sixteenth century, or about 100 years earlier?
This criticism of the "history of the index card" does, of course, not diminish Linnaeus's other achievements in any way. The article has other problems as well.
A propos Linnaeus, Weinberger (2007) claims that "Linnaeus's organization took the shape it did in part because he constructed it out of paper." "he used paper - atoms - to think through the order of the natural world." Whether this kind of reductionism can be maintained is also highly questionable - or so I would claim. This seems to be at best an over-simplifiction. It may well be that paper cards were a necessary condition in the eighteenth century, but that does not mean that they were also sufficient conditions. To his credit, Weinberger says "in part." Others have made such reductionist claims without any qualification.
1. Let me be clear: I don't claim that they invented the index card either. I am just claiming that they have just as much right as Linnaeus. Index cards were invented much later.