If you are going to build something in the air it is always better to build castles than houses of cards.

What we have to discover for ourselves leaves behind in our mind a pathway that can be used on another occasion.

Nothing can contribute more to peace of soul than the lack of any opinion whatever.

I made the journey to knowledge like dogs who go for walks with their masters, a hundred times forward and backward over the same territory; and when I arrived I was tired.

To grow wiser means to learn to know better and better the faults to which this instrument with which we feel and judge can be subject.

We now possess four principles of morality: 1) a philosophical: do good for its own sake, out of respect for the law; 2) a religious: do good because it is God's will, out of love of God; 3) a human: do good because it will promote your happiness, out of self-love; 4) a political: do good because it will promote the welfare of the society of which you are a part, out of love of society having regard to yourself. But is this not all one single principle, only viewed from different sides?

I cannot say whether things will get better if we change; what I can say is they must change if they are to get better.