The man who lives within his income is naturally contented with his situation, which, by continual, though small accumulations, is growing better and better every day.
 Adam Smith, The Theory of Moral Sentiments (1759). copy citation

Context

“He cannot therefore but approve, and even applaud, that proper exertion of self-command, which enables them to act as if their present and their future situation affected them nearly in the same manner in which they affect him. The man who lives within his income is naturally contented with his situation, which, by continual, though small accumulations, is growing better and better every day. He is enabled gradually to relax, both in the rigour of his parsimony and in the severity of his application; and he feels with double satisfaction this gradual increase of ease and enjoyment, from having felt before the hardship which attended the want of them.” source