The fourfold root of the principle of sufficent reason is "Anything perceived has a cause. All conclusions have premises. All effects have causes. All actions have motives.

A man never is happy, but spends his whole life in striving after something which he thinks will make him so; he seldom attains his goal, and when he does, it is only to be disappointed; he is mostly shipwrecked in the end, and comes into harbor with mast and rigging gone. And then, it is all one whether he has been happy or miserable; for his life was never anything more than a present moment always vanishing; and now it is over.

Optimism is not only a false but also a pernicious doctrine, for it presents life as a desirable state and man's happiness as its aim and object. Starting from this, everyone then believes he has the most legitimate claim to happiness and enjoyment. If, as usually happens, these do not fall to his lot, he believes that he suffers an injustice, in fact that he misses the whole point of his existence.

Animals learn death first at the moment of death;...man approaches death with the knowledge it is closer every hour, and this creates a feeling of uncertainty over his life, even for him who forgets in the business of life that annihilation is awaiting him. It is for this reason chiefly that we have philosophy and religion.

A man can surely do what he wills to do, but cannot determine what he wills.

At bottom, every state regards another as a gang of robbers who will fall upon it as soon as there is an opportunity.

Talent hits a target no one else can hit; Genius hits a target no one else can see.