Man's life cannot "be lived" by repeating the pattern of his species; he must live. Man is the only animal that can be bored, that can be discontented, that can feel evicted from paradise. Man is the only animal for whom his own existence is a problem which he has to solve and from which he cannot escape. He cannot go back to the prehuman state of harmony with nature; he must proceed to develop his reason until he becomes the master of nature, and of himself.

Man is the only animal whose fear of embarrassment can overcome his instinct for self-preservation.

Man is the only creature who refuses to be what he is.

Man is the only living being who has a developed self-awareness and death-awareness.

Man is the only animal whose desires increase as they are fed; the only animal that is never satisfied.

[Man] is the only animal who lives outside of himself, whose drive is in external things — property, houses, money, concepts of power. He lives in his cities and his factories, in his business and job and art. But having projected himself into these external complexities, he is them. His house, his automobile are a part of him and a large part of him. This is beautifully demonstrated by a thing doctors know — that when a man loses his possessions a very common result is sexual impotence.

Man is the only animal that laughs and weeps; for he is the only animal that is struck with the difference between what things are, and what they ought to be.

Man is and remains an animal.Here a beast of prey, there a housepet, but always an animal.

Man is the only living species that has the power to act as his own destroyer—and that is the way he has acted through most of his history.

Man, who is the only creature on earth which God willed for itself, can fully find himself only through a sincere gift of himself.

Man is not born to solve the problem of the universe, but to find out what he has to do; and to restrain himself within the limits of his comprehension.

Man is the only animal that deals in that atrocity of atrocities War. He is the only one that gathers his brethren about him and goes forth in cold blood and calm pulse to exterminate his kind. He is the only animal that for sordid wages will march out... and help to slaughter strangers of his own species who have done him no harm and with whom he has no quarrel.... And in the intervals between campaigns he washes the blood off his hands and works for the universal brotherhood of man with his mouth.

The problem with people is that they're only human.

Man prides himself on being the only animal who can modify his nature, yet when he chooses to do so he is called a phony.