collected must be classified sooner or later; otherwise it would be
necessary, when occasion arose, to deal separately with the materials
bearing on a given point, to read right through the whole series of
note-books, and this laborious process would have to be repeated every
time a new detail was wanted. If this method seems attractive at first,
it is because it appears to save time. But this is false economy; the
ultimate result is, an enormous addition to the labour of search, and
great difficulty in combining the materials.

Others, well understanding the advantages of systematic classification,
have proposed to fit their materials, as fast as collected, into their
appropriate places in a prearranged scheme. For this purpose they use
note-books of which every page has first been provided with a heading.
Thus all the entries of the same kind are close to one another. This
system leaves something to be desired; for additions will not always
fit without inconvenience into their proper place; and the scheme of
classification, once adopted, is rigid, and can only be modified with
difficulty. Many librarians used to draw up their catalogues on this
plan, which is now universally condemned.

There is a still more barbarous method, which need not receive more than
passing mention. This is simply to register documents in the memory
without taking written notes. This method has been used. Historians
endowed with excellent memories, and lazy to boot, have indulged this
whim, with the result that their quotations and references are mostly
inexact. The human memory is a delicate piece of registering apparatus,
but it is so little an instrument of precision that such presumption is
inexcusable.

Every one admits nowadays that it is advisable to collect materials on
separate cards or slips of paper. The notes from each document are
entered upon a loose leaf furnished with the precisest possible
indications of origin. 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. As for documents which are interesting from several points of
view, and which ought to appear in several groups, it is sufficient to
enter them several times over on different sl