Man is his own worst enemy.

A man would have no pleasures in discovering all the beauties of the universe, even in heaven itself, unless he had a partner to whom he might communicate his joys.

It is certain that memory contains not only philosophy, but all the arts and all that appertain to the use of life.

When I consider the wonderful activity of the mind, so great a memory of what is past, and such a capacity of penetrating into the future: when I behold such a number of arts and sciences, and such a multitude of discoveries hence arising,--I believe and am firmly persuaded that a nature which contains so many things within itself cannot be mortal.

I will go further, and assert that nature without culture can often do more to deserve praise than culture without nature.

As in the case of wines that improve with age, the oldest friendships ought to be the most delightful.

The existence of virtue depends entirely upon its use.