Aristotle made, in one of the most admirable and just passages of his Nicomachean Ethics, the remark that happiness, or rather eudaimonia, is not a thing lent by chance, as the ignorant suppose who confuse it with prosperity and luck, but what results from our own efforts. This means that true happiness is not a favor granted by fate, but the work of a life guided by wisdom. What distinguishes one man from another, what makes a man happy or unhappy, rests on three things, divided according to three fundamental realities. First, what he is, that is, his personality, with everything it gives him: health, strength, beauty, temperament, moral character, and the intelligence and culture that accompany them. Second, what he has, that is, his goods, his fortune, his property. Third, what he appears to be, that is, the opinion others hold of him: honor, rank, glory. Now the most essential difference between men, the one that determines their deep happiness or misery, lies neither in the goods they possess nor in the gaze of others: it lies in what they themselves are. For what one has can cease to be ours through chance or ruin; what one is, on the contrary, never leaves us. The world exists for each of us only as he sees and understands it: each man has the world as he himself is. A man's life, with all its events, resembles a landscape that different distances or lightings distort and diversify; but what above all changes the coloring of this life is the very gaze of the one who travels through it. If one could see the smiles of Fortune, one would almost never think of a happy lot; one would think of what comes to each man according to what he is. Indeed, external events affect us only insofar as they pass through the filter of our inner constitution; the same event is for one a source of pain, for another a source of joy, according to the nature of the mind that receives it. This is why ambition, pride, envy can procure no lasting happiness: they presuppose that well-being resides in others, whereas it can only reside in ourselves. The man who has worth only through his possessions or the esteem of others is a man whose worth can be taken from him overnight. On the contrary, he who possesses within himself a lofty intelligence, a lively and rich sensibility, a calm mind and a masterful will, carries his treasure wherever he goes; he enjoys a source of pleasure that never runs dry. Hence great minds are, at bottom, the happiest of men, not on account of the world around them, but on account of the world they carry within. It is in oneself, far more than in external things, that the principal source of contentment in life is found. The glorious experience of the world teaches everyone, indeed, that the satisfaction of our desires depends far more on our inner disposition than on the degree to which circumstances have conformed to our wishes. The wealthy man laden with goods languishes in the same sadness as the poor man, if his mind is empty; and the man of modest condition, rich in thought, finds in his own existence joys unknown to holders of fortune. An eminent personality gives life a value that neither wealth nor renown can give it. For the greatest source of happiness is the man himself, not the external world; the ancients already sensed this when they placed wisdom above power. This is what must always be kept before one's eyes: if one wants to be happy, it is not toward the gifts of Fortune that one should reach out, but toward oneself that one must first apply oneself. Everything within us, nothing outside us, truly belongs to us; and the only good that is not lost is the one that grows with us, that increases through the effort of thought, and that can be disputed by us neither by death nor by human weakness. For the deep and rich man, the world is full of interests and subjects of contemplation; for the poor spirit, it is desert and monotonous, whatever his riches. Thus each man is, in the final analysis, the cause of his own happiness and his own misery: the world in which a man lives is not the same for all; each man lives in a world apart, shaped by what he is. From this follows the conclusion that sums up all practical wisdom: cultivate what you are, for what you are alone remains yours through all the vicissitudes of fate.