of a satisfactory theory of the planetary motions or of the facts of
growth and reproduction. As the study of special questions was pursued
further, it became advisable to hand over the treatment of first one and
then another group of closely interconnected questions to students who
would pursue them independently of research into ultimate
presuppositions. This is how Geometry, Astronomy, Biology came, in
ancient times, to be successively detached from general Philosophy. The
separation of Psychology--the detailed study of the processes of mental
life--from Philosophy hardly goes back beyond the days of our fathers,
and the separation of such studies as 'sociology' from general
Philosophy may be said to belong quite definitely to our own time. If
our children have leisure for study at all, no doubt they will see the
process carried much further. But it is important to bear in mind that
neither Philosophy in the narrower sense nor Science in the narrower
sense will be fruitfully prosecuted unless the men who are working at
each understand that their own labours are only part of a single
undivided work. Without a genuine grasp of some department of detailed
facts no man is likely to achieve much in the search for principles, for
it is by analysis of facts that principles are to be found, and without
real insight into broad general principles the worker in detail is
likely to achieve nothing but confusion. The antagonism between
'philosophers' and 'men of science' so characteristic of the last half
of the nineteenth century has been productive of nothing but evil. It
has given us 'philosophers' whose knowledge about the facts with which
serious thinking has to deal has been hopelessly inaccurate; it has also
given us 'men of science' who have been 'ageometretes' and have, by
consequence, when forced to offer some account of first principles,
taken refuge in the wildest and weirdest improvisation. For really
fruitful work we need the union in one person of the 'man of science'
and the 'philosopher', or at least the most intimate co-operation