ecline and then their rise, and again their fall, form a
chapter in this history of the human mind; we become critics even by
this literary chronology, and this appraisement of auctioneers. The
favourite book of every age is a certain picture of the people. The
gradual depreciation of a great author marks a change in knowledge or in
taste.

But it is imagined that we are not interested in the history of
indifferent writers, and scarcely in that of the secondary ones. If none
but great originals should claim our attention, in the course of two
thousand years we should not count twenty authors! Every book, whatever
be its character, may be considered as a new experiment made by the
human understanding; and as a book is a sort of individual
representation, not a solitary volume exists but may be personified, and
described as a human being. Hints start discoveries: they are usually
found in very different authors who could go no further; and the
historian of obscure books is often preserving for men of genius
indications of knowledge, which without his intervention we should not
possess! Many secrets we discover in bibliography. Great writers,
unskilled in this science of books, have frequently used defective
editions, as Hume did the castrated Whitelocke; or, like Robertson, they
are ignorant of even the sources of the knowledge they would give the
public; or they compose on a subject which too late they discover had
been anticipated. Bibliography will show what has been done, and suggest
to our invention what is wanted. Many have often protracted their
journey in a road which had already been worn out by the wheels which
had traversed it: bibliography unrolls the whole map of the country we
purpose travelling over--the post-roads and the by-paths.

Every half-century, indeed, the obstructions multiply; and the Edinburgh
prediction, should it approximate to the event it has foreseen, may more
reasonably terrify a far distant posterity. Mazzuchelli declared, after
his laborious researches in Italian literature, that one of his more
recent predecessors, who had commenced a similar work, had collected
notices of forty thousand writers--and yet, he adds, my work must
increase that number to ten thousand more! Mazzuchelli said this in
1753; and the amount of nearly a century must now be added, for the
presses of Italy have not been inactive.

But the literature of Germany, of France, and of England has exceeded
the multiplic