Virtue is as little to be acquired by learning as genius; nay, the idea is barren, and is only to be employed as an instrument, in the same way as genius in respect to art. It would be as foolish to expect that our moral and ethical systems would turn out virtuous, noble, and holy beings, as that our aesthetic systems would produce poets, painters, and musicians.
For, after all, the foundation of our whole nature, and, therefore, of our happiness, is our physique, and the most essential factor in happiness is health, and, next in importance after health, the ability to maintain ourselves in independence and freedom from care.
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.
Just as the largest library, badly arranged, is not so useful as a very moderate one that is well arranged, so the greatest amount of knowledge, if not elaborated by our own thoughts, is worth much less than a far smaller volume that has been abundantly and repeatedly thought over.
Monotheistic religions alone furnish the spectacle of religious wars, religious persecutions, heretical tribunals, that breaking of idols and destruction of images of the gods, that razing of Indian temples and Egyptian colossi, which had looked on the sun 3,000 years: just because a jealous god had said, Thou shalt make no graven image.