ABSTRACT
Ordinary workers collect and classify materials useful for their individual studies. Hence certain differences arise. For example, the arrangement by subjects, on a predetermined system, which is so little to be recommended for great collections, often provides those who are composing monographs on their own account with a scheme of classification preferable to any other. Whoever studies a point of history is obliged, first of all, to classify his sources. To arrange, in a rational and convenient manner, the verified materials before making use of them, is an apparently humble, but really very important, part of the historian’s profession. The method of slips is not without its drawbacks. Each slip ought to be furnished with precise references to the source from which its contents have been derived; consequently, if a document has been analysed upon fifty different slips, the same references must be repeated fifty times.
