When Need Arises
Meanwhile, as they read, they should have notebooks at hand, in which they may copy out the more elegant phrases and sentences; or let them have some blank pages bound in at the end of the books they read, and on them they may note down the number of the page in question and the heading of some remarkable topic. Then, when need arises, they will be able to make reference to it.
(Caspar Barlaeus, “Methodus Studiorum”, in Hugo Grotius et al., Dissertationes de studiis instituendis, Apud Ludovicum Elzevirium, Amsterdam, 1645, p. 353).