The unhappiness of people is due to their ignorance of nature.
Men always fool themselves when they give up experience for systems born of the imagination. Man is the work of nature, he exists in nature, he is subject to its laws, he can not break free, he can not leave even in thought; it is in vain that his spirit wants to soar beyond the bounds of the visible world, he is always forced to return.
The source of man's unhappiness is his ignorance of Nature.
