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.
The fourfold root of the principle of sufficent reason is "Anything perceived has a cause. All conclusions have premises. All effects have causes. All actions have motives.
Many books serve merely to show how many ways there are of being wrong, and how far astray you yourself would go if you followed their guidance. You should read only when your own thoughts dry up.
We will gradually become indifferent to what goes on in the minds of other people when we acquire a knowledge of the superficial nature of their thoughts, the narrowness of their views and of the number of their errors. Whoever attaches a lot of value to the opinions of others pays them too much honor.
We should be surprised that a matter that generally plays such an important part in the life of man has hitherto been almost entirely disregarded by philosophers, and lies before us as raw and untreated material.
Education perverts the mind since we are directly opposing the natural development of our mind by obtaining ideas first and observations last. This is why so few men of learning have such sound common sense as is quite common among the illiterate.
Buying books would be a good thing if one could also buy the time to read them in: but as a rule the purchase of books is mistaken for the appropriation of their contents.
When you look back on your life, it looks as though it were a plot, but when you are into it, it's a mess: just one surprise after another. Then, later, you see it was perfect.
There is only one inborn erroneous notion ... that we exist in order to be happy ... So long as we persist in this inborn error ... the world seems to us full of contradictions. For at every step, in great things and small, we are bound to experience that the world and life are certainly not arranged for the purpose of maintaining a happy existence ... hence the countenances of almost all elderly persons wear the expression of ... disappointment.
The inexpressible depth of music, so easy to understand and yet so inexplicable, is due to the fact that it reproduces all the emotions of our innermost being, but entirely without reality and remote from its pain… Music expresses only the quintessence of life and its events, never these themselves.