er wishes to study any subject, let him beware of rushing
to the newest books upon it, and confining his attention to them
alone, under the notion that science is always advancing, and that the
old books have been drawn upon in the writing of the new. They have
been drawn upon, it is true; but how? The writer of the new book often
does not understand the old books thoroughly, and yet he is unwilling
to take their exact words; so he bungles them, and says in his own bad
way that which has been said very much better and more clearly by the
old writers, who wrote from their own lively knowledge of the subject.
The new writer frequently omits the best things they say, their most
striking illustrations, their happiest remarks; because he does not
see their value or feel how pregnant they are. The only thing that
appeals to him is what is shallow and insipid.

It often happens that an old and excellent book is ousted by new
and bad ones, which, written for money, appear with an air of great
pretension and much puffing on the part of friends. In science a man
tries to make his mark by bringing out something fresh. This often
means nothing more than that he attacks some received theory which
is quite correct, in order to make room for his own false notions.
Sometimes the effort is successful for a time; and then a return is
made to the old and true theory. These innovators are serious about
nothing but their own precious self: it is this that they want to put
forward, and the quick way of doing so, as they think, is to start a
paradox. Their sterile heads take naturally to the path of negation;
so they begin to deny truths that have long been admitted--the vital
power, for example, the sympathetic nervous system, _generatio
equivoca_, Bichat's distinction between the working of the passions
and the working of intelligence; or else they want us to return to
crass atomism, and the like. Hence it frequently happens that _the
course of science is retrogressive._

To this class of writers belong those translators who not only
translate their author but also correct and revise him; a proceeding
which always seems to me impertinent. To such writers I say: Write
books yourself which are worth translating, and leave other people's
works as they are!

The reader should study, if he can, the real authors, the men who
have founded and discovered things; or, at any rate, those who are
recognized as the great masters in every branch of kn