It is terrible to seehow a single unclear idea, a single formula without meaning, lurking in a young man's head, willsometimes act like an obstruction of inert matter in an artery, hindering the nutrition of the brain,and condemning its victim to pine away in the fullness of his intellectual vigor and in the midst ofintellectual plenty.

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.'" [6]

come up with inferences