An introduction to mathematics, by A. N. Whitehead.

12 INTRODUCTION TO MATHEMATICS
from our sensations. We see, and hear, and
taste, and smell, and feel hot and cold, and
push, and rub, and ache, and tingle. These
are just our own personal sensations: my
toothache cannot be your toothache, and my
sight cannot be your sight. But we ascribe
the origin of these sensations to relations between the things which form the external
world. Thus the dentist extracts not the
toothache but the tooth. And not only so,
we also endeavour to imagine the world as
one connected set of things which underlies
all the perceptions of all people. There is not
one world of things for my sensations and another for yours, but one world in which we
both exist. It is the same tooth both for
dentist and patient. Also we hear and we
touch the same world as we see.
It is easy, therefore, to understand that
we want to describe the connections between
these external things in some way which
does not depend on any particular sensations, nor even on all the sensations of any
particular person. The laws satisfied by the
course of events in the world of external
things are to be described, if possible, in a
neutral universal fashion, the same for blind
men as for deaf men, and the same for beings
with faculties beyond our ken as for normal
human beings.
But when we have put aside our immediate