The principal effect of the passions is that they incite and persuade the mind to will the events for which they prepared the body.

The two operations of our understanding, intuition and deduction, on which alone we have said we must rely in the acquisition of knowledge.

An optimist may see a light where there is none, but why must the pessimist always run to blow it out?

If ... it is not in my power to arrive at the knowledge of any truth, I may at least do what is in my power, namely, suspend judgement.

Intuition is the undoubting conception of a pure and attentive mind, which arises from the light of reason alone, and is more certain than deduction.

Omnia apud me mathematica fiunt.

It is not enough to have a good mind. The main thing is to use it well.