The doors of wisdom are never shut.

So much for industry, my friends, and attention to one's own business; but to these we must add frugality if we would make our industry more certainly successful. A man may, if he knows not how to save as he gets, keep his nose all his life to the grindstone, and die not worth a grout at last.

For having lived long, I have experienced many instances of being obliged, by better information or fuller consideration, to change opinions, even on important subjects, which I once thought right but found to be otherwise.

It is a grand mistake to think of being great without goodness and I pronounce it as certain that there was never a truly great man that was not at the same time truly virtuous.

Idle hands are the devil's playthings.

I am in the prime of senility.

Perhaps the history of the errors of mankind, all things considered, is more valuable and interesting than that of their discoveries. Truth is uniform and narrow; it constantly exists, and does not seem to require so much an active energy, as a passive aptitude of the soul in order to encounter it. But error is endlessly diversified; it has no reality, but is the pure and simple creation of the mind that invents it. In this field the soul has room enough to expand herself, to display all her boundless faculties, and all her beautiful and interesting extravagancies and absurdities.