He will do so when the pleasure of looking at comfort is greater than the pleasure of feeling it.

And in certain states of mind and body this is very often the case.

But let him be sleepy and really in need of rest, the selfish impulse will at once eclipse the unselfish, and, unless under the action of some alien motive, he will keep the arm-chair for himself.

So, too, in the case of the two epicures, if there be sufficient of the best dainties for both, each will feel that it is so much the better.

But whenever the dainties in question cannot be divided, it will be the tendency of each to take them furtively for himself.
And when we come to the conditions of happiness the matter will be just the same.