I accept no principles of physics which are not also accepted in mathematics.

The only secure knowledge is that I exist.

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.

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

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

For each of us there is a set limit to our intellectual powers which we cannot pass.

If I simply refrain from making a judgment in cases where I do not perceive the truth with sufficient clarity and distinctness, then it is clear that I am behaving correctly and avoiding error.