It is chiefly a matter of custom. Our faces, exposed to cold, do get cold, but they do not feel cold because the nerves by which we feel cold are accustomed to this state of affairs and take no notice of it. In fact, all nerves act in this way. Messages travel along them only when there is a change in usual condition of the body. We tolerate, without noticing them, degrees of cold to which we are accustomed in our face and hands; but we actually feel that our feet are cold if we expose them. Yet people who are accustomed to bare feet feel no more and suffer no more from them than we do from bare hands. On a winter day we may not notice that our noses and ear tips are cold, even when they are quite cold. You soon find that they are if you put a hand against them. There is a tremendous difference between being cold and feeling cold.

This rule about being accustomed to certain weather conditions and the way in which nerves are affected by them, also explains many other things – for instance, why the countryman can not at first sleep in the town on account of noise, while the townsman can not sleep in the country on account of silence. After some experience, however, the countryman gets used to the noise and the townsman gets used to the silence, and both sleep soundly.