From Chekhov's "Three Years"

Laptev said nothing. Yartsev walked up and down the study, looking at the pictures he had seen so many times before, and said with a sigh: 

"Yes, my dear fellow, I am three years older than you are, and it's too late for me to think of real love, and in reality a woman like Polina Nikolaevna is a godsend to me, and, of course, I shall get on capitally with her till we're both old people; but, goodness knows why, one still regrets something, one still longs for something, and I still feel as though I am lying in the Vale of Daghestan and dreaming of a ball. In short, man's never satisfied with what he has."