Leopardi, 11

Happiness can be found only in the perfection of which a being is capable. A being is not perfect if all of its faculties are not perfectly in accord with one another, perfectly developed according to their nature, and if each of these does not enjoy its proper object to the full extent of its capability. It is not perfect if it does not conform to the laws resulting from its nature. But in order to conform to them, it needs to know what they are. Therefore, man cannot be happy unless he knows himself and the necessary relationships he has with other beings. (227)

Leopardi, Giacomo, and Michael Caesar. Zibaldone. New York: Farrar, Straus and Giroux, 2013.