gent discussion suggests new ideas
and continually carries the mind to a higher level of thought. We must
not regard the typical scientific worker, even of the highest class, as
one who, having chosen his special field and met with success in
cultivating it, has only to be supplied with the facilities he may be
supposed to need in order to continue his work in the most efficient
way. What we have to deal with is not a fixed and permanent body of
learned men, each knowing all about the field of work in which he is
engaged, but a changing and growing class, constantly recruited by
beginners at the bottom of the scale, and constantly depleted by the
old dropping away at the top. No view of the subject is complete which
does not embrace the entire activity of the investigator, from the tyro
to the leader. The leader himself, unless engaged in the prosecution of
some narrow specialty, can rarely be so completely acquainted with his
field as not to need information from others. Without this, he is
constantly liable to be repeating what has already been better done
than he can do it himself, of following lines which are known to lead
to no result, and of adopting methods shown by the experience of others
not to be the best. Even the books and published researches to which he
must have access may be so voluminous that he cannot find time to
completely examine them for himself; or they may be inaccessible. All
this will make it clear that, with an occasional exception, the best
results of research are not to be expected except at centres where
large bodies of men are brought into close personal contact.

In addition to the power and facility acquired by frequent discussion
with his fellows, the appreciation and support of an intelligent
community, to whom the investigator may, from time to time, make known
his thoughts and the results of his work, add a most effective
stimulus. The greater the number of men of like minds that can be
brought together and the larger the community which interests itself in
what they are doing, the more rapid will be the advance and the more
effective the work carried on. It is thus that London, with its
munificently supported institutions, and Paris and Berlin, with their
bodies of investigators supported either by the government or by
various foundations, have been for more than three centuries the great
centres where we find scientific activity most active and most
effective. Looking at this undo