The only thing that one really knows about human nature is that it changes. Change is the one quality we can predicate of it. The systems that fail are those that rely on the permanency of human nature, and not on its growth and development. The error of Louis XIV was that he thought human nature would always be the same. The result of his error was the French Revolution. It was an admirable result.
Look at the trees, look at the birds, look at the clouds, look at the stars… and if you have eyes you will be able to see that the whole existence is joyful. Everything is simply happy. Trees are happy for no reason; they are not going to become prime ministers or presidents and they are not going to become rich and they will never have any bank balance. Look at the flowers - for no reason. It is simply unbelievable how happy flowers are.
Every rational creature has all nature for his dowry and estate. It is his, if he will. He may divest himself of it; he may creepinto a corner, and abdicate his kingdom, as most men do, but he is entitled to the world by his constitution.
For many parts of Nature can neither be invented with sufficient subtlety, nor demonstrated with sufficient perspicuity, nor accommodated unto use with sufficient dexterity, without the aid and intervening of the mathematics, of which sort are perspective, music, astronomy, cosmography, architecture, engineery, and divers others.
The more one analyses people, the more all reasons for analysis disappear. Sooner or later one comes to that dreadful universal thing called human nature.
If we study Nature attentively in its great evolutions as in its minutest works, we cannot fail to recognize the possibility of enchantment - giving to that word its exact significance.
But nothing is more estimable than a physician who, having studied nature from his youth, knows the properties of the human body, the diseases which assail it, the remedies which will benefit it, exercises his art with caution, and pays equal attention to the rich and the poor.