To know what people really think, pay regard to what they do, rather than what they say.

I think, therefore I am.

It is easy to hate and it is difficult to love. This is how the whole scheme of things works. All good things are difficult to achieve; and bad things are very easy to get.

Doubt is the origin of wisdom.

The reading of all good books is like a conversation with the finest minds of past centuries.

In order to improve the mind, we ought less learn than to contemplate.

Illusory joy is often worth more than genuine sorrow.

If you choose not to decide, you still have made a choice.

I hope that posterity will judge me kindly, not only as to the things which I have explained, but also to those which I have intentionally omitted so as to leave to others the pleasure of discovery.

Except our own thoughts, there is nothing absolutely in our power.

So blind is the curiosity by which mortals are possessed, that they often conduct their minds along unexplored routes, having no reason to hope for success, but merely being willing to risk the experiment of finding whether the truth they seek lies there.

Divide each difficulty into as many parts as is feasible and necessary to resolve it.

Whenever anyone has offended me, I try to raise my soul so high that the offense cannot reach it.

When it is not in our power to determine what is true, we ought to follow what is most probable.

When I consider this carefully, I find not a single property which with certainty separates the waking state from the dream. How can you be certain that your whole life is not a dream?

I am indeed amazed when I consider how weak my mind is and how prone to error.