7

those which would make it good for logical
purposes. The truth is that the mathemati-
cian and the logician meet in one depart-
ment on a common highway. They meet;
but one is facing one way while the other is
facing just the other way. Each of them, it is
true, finds it interesting to turn around occa-
sionally and take a glance in the opposite di-
rection.

The mathematician, however, has little or
nothing to learn of the logician. Mathematics
differs from all the special sciences whether
of physics or of psychics in never encountering
logical difficulties, which it does not lie
entirely within his own competence to resolve.