The most certain sign of wisdom is cheerfulness.

The truth of these days is not that which really is, but what every man persuades another man to believe.

Death, they say, acquits us of all obligations.

Whenever a new finding is reported to the world people say - It is probably not true. Later on, when the reliability of a new finding has been fully confirmed, people say - OK, it may be true but it has no real significance. At last, when even the significance of the finding is obvious to everybody, people say - Well, it might have some significance, but the idea is not new.

I honor most those to whom I show least honor; and where my soul moves with great alacrity, I forget the proper steps of ceremony.

It is probable that the principal credit of miracles, visions, enchantments, and such extraordinary occurrences comes from the power of imagination, acting principally upon the minds of the common people, which are softer.

I study myself more than any other subject. That is my metaphysics, that is my physics.