Too little liberty brings stagnation, and too much brings chaos.

But I simply can't stand a view limited to this earth, I feel life is so small unless it has windows into other worlds...I like mathematics largely because it is not human.

Love can only flourish as long as it is free and spontaneous; it tends to be killed by the thought that it is a duty. To say that it is your duty to love so-and-so is the surest way to cause you to hate him or her.

If everything must have a cause, then God must have a cause. If there can be anything without a cause, it may just as well be the world as God, so that there cannot be any validity in that argument... The idea that things must have a beginning is really due to the poverty of our imagination.

Men are born ignorant, not stupid. They are made stupid by education.

Organic life, we are told, has developed gradually from the protozoon to the philosopher, and this development, we are assured, is indubitably an advance. Unfortunately it is the philosopher, not the protozoon, who gives us this assurance.

All the time that he can spare from the adornment of his person, he devotes to the neglect of his duties.