Perfectibility, the human capacity to improve, may be the source of all human misfortunes

It would be a melancholy necessity for us to be obliged to allow, that this distinctive and almost unlimited faculty is the source of all man's misfortunes; that it is this faculty, which, though by slow degrees, draws them out of their original condition, in which his days would slide away insensibly in peace and innocence; that it is this faculty, which, in a succession of ages, produces his discoveries and mistakes, his virtues and his vices, and, at long run, renders him both his own and nature's tyrant.