ow that appeals to him. An old and excellent book is frequently
shelved for new and bad ones; which, written for the sake of money, wear
a pretentious air and are much eulogised by the authors' friends. In
science, a man who wishes to distinguish himself brings something new to
market; this frequently consists in his denouncing some principle that
has been previously held as correct, so that he may establish a wrong
one of his own. Sometimes his attempt is successful for a short time,
when a return is made to the old and correct doctrine. These innovators
are serious about nothing else in the world than their own priceless
person, and it is this that they wish to make its mark. They bring this
quickly about by beginning a paradox; the sterility of their own heads
suggests their taking the path of negation; and truths that have long
been recognised are now denied--for instance, the vital power, the
sympathetic nervous system, _generatio equivoca_, Bichat's distinction
between the working of the passions and the working of intelligence, or
they return to crass atomism, etc., etc. Hence _the course of science is
often retrogressive_.

To this class of writers belong also those translators who, besides
translating their author, at the same time correct and alter him, a
thing that always seems to me impertinent. Write books yourself which
are worth translating and leave the books of other people as they are.
One should read, if it is possible, the real authors, the founders and
discoverers of things, or at any rate the recognised great masters in
every branch of learning, and buy second-hand _books_ rather than read
their _contents_ in new ones.

It is true that _inventis aliquid addere facile est_, therefore a man,
after having studied the principles of his subject, will have to make
himself acquainted with the more recent information written upon it. In
general, the following rule holds good here as elsewhere, namely: what
is new is seldom good; because a good thing is only new for a short
time.

What the address is to a letter the _title_ should be to a book--that
is, its immediate aim should be to bring the book to that part of the
public that will be interested in its contents. Therefore, the title
should be effective, and since it is essentially short, it should be
concise, laconic, pregnant, and if possible express the contents in a
word. Therefore a title that is prolix, or means nothing at all, or that
is indirec