The man who feels little for his own misfortunes must always feel less for those of other people, and be less disposed to relieve them.
 Adam Smith, The Theory of Moral Sentiments (1759). copy citation

Context

“but which, amidst the natural and moral evils infesting the world, lays its account and is contented to suffer a little from both, is a blessing to the man himself, and gives ease and security to all his companions. Our sensibility, however, both to our own injuries and to our own misfortunes, though generally too strong, may likewise be too weak. The man who feels little for his own misfortunes must always feel less for those of other people, and be less disposed to relieve them. The man who has little resentment for the injuries which are done to himself, must always have less for those which are done to other people, and be less disposed either to protect or to avenge them.” source