In its essence life is monotonous. Happiness therefore depends on a reasonably thorough adaptation to life’s monotony. By making ourselves monotonous, we make ourselves equal to life. Thus we live to the full. And living to the full is to be happy...It seems, at first glance, that new things are what give pleasure to the mind; but there aren’t many new things, and each one is new only once. Our sensibility, furthermore, is limited, and it doesn’t vibrate indefinitely. Too many new things will eventually get tiresome, since our sensibility can’t keep up with all the stimulations it receives.
(Hat tip: 3QD)