no idea of the manner in which they are affected but by conceiving what
we ourselves should feel in the like situation. Though our brother is
upon the rack, as long as we ourselves are at our ease our senses will
never inform us of what he suffers. They never did, and never can, carry
us beyond our own person, and it is by the imagination only that we can
form any conception of what are his sensations. Neither can that faculty
help us to this any other way than by representing to us what would be
our own, if we were in his case. It is the impressions of our own senses
only, not those of his, which our imaginations copy. By the imagination
we place ourselves in his situation, we conceive ourselves enduring all
the same torments, we enter as it were into his body and become in some
measure the same person with him, and thence form some idea of his
sensations, and even feel something which, though weaker in degree, is
not altogether unlike them. His agonies, when they are thus brought home
to ourselves, when we have thus adopted and made them our own, begin at
last to affect us, and we then tremble and shudder at the thought of
what he feels. For, as to be in pain or distress of any kind excites the
most excessive sorrow, so to conceive or to imagine that we are in it
excites some degree of the same emotion, in proportion to the vivacity
or dulness of the conception.

That this is the source of our fellow-feeling for the misery of others,
that it is by changing places in fancy with the sufferer that we come
either to conceive or to be affected by what he feels, may be
demonstrated by many obvious observations, if it should not be thought
sufficiently evident of itself. When we see a stroke aimed, and just
ready to fall upon the leg or arm of another person, we naturally shrink
and draw back our own leg or our own arm; and when it does fall, we feel
it in some measure and are hurt by it as well as the sufferer. The mob,
when they are gazing at a dancer on the slack rope, naturally writhe and
twist and balance their own bodies as they see him do, and as they feel
that they themselves must do if in his situation. Persons of delicate
fibers and a weak constitution of body complain that in looking on the
sores and ulcers which are exposed by beggars in the streets they are
apt to feel an itching or uneasy sensation in the corresponding part of
their own bodies. The horror which they conceive at the misery of those
wretches aff