I notice, also, that the nature of body is such that none
of its parts can be moved by another part a little way off
which cannot also be moved in the same way by each one of the
parts which are between the two, although this more remote
part does not act at all. As, for example, in the cord ABCD
[which is in tension] if we pull the last part D, the first
part A will not be moved in any way differently from what
would be the case if one of the intervening parts B or C were
pulled, and the last part D were to remain unmoved. And in
the same way, when I feel pain in my foot, my knowledge of
physics teaches me that this sensation is communicated by
means of nerves dispersed through the foot, which, being
extended like cords from there to the brain, when they are
contracted in the foot, at the same time contract the inmost
portions of the brain which is their extremity and place of
origin, and then excite a certain movement which nature has
established in order to cause the mind to be affected by a
sensation of pain represented as existing in the foot.
Pages:
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141