I have long held the opinion that the amount of noise that anyone can bear undisturbed stands in inverse proportion to his mental capacity and therefore be regarded as a pretty fair measure of it.

As the biggest library if it is in disorder is not as useful as a small but well-arranged one, so you may accumulate a vast amount of knowledge but it will be of far less value to you than a much smaller amount if you have not thought it over for yourself; because only through ordering what you know by comparing every truth with every other truth can you take complete possession of your knowledge and get it into your power. You can think about only what you know, so you ought to learn something; on the other hand, you can know only what you have thought about.

Because people have no thoughts to deal in, they deal cards, and try and win one another's money. Idiots!

Happiness consists in frequent repetition of pleasure

This is the case with many learned persons; they have read themselves stupid.

We seldom think of what we have but always of what we lack. Therefore, rather than grateful, we are bitter.

To buy books would be a good thing if we could also buy the time to read them; but the purchase of books is often mistaken for the assimilation and mastering of their contents.