Two Chinamen visiting Europe went to the theatre for the first time. One of them occupied himself with trying to understand the theatrical machinery, which he succeeded in doing. The other, despite his ignorance of the language, sought to unravel the meaning of the play. The former is like the astronomer, the latter the philosopher.
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.
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.
It is only a man's own fundamental thoughts that have truth and life in them. For it is these that he really and completely understands. To read the thoughts of others is like taking the remains of someone else's meal, like putting on the discarded clothes of a stranger.
Genius is its own reward; for the best that one is, one must necessarily be for oneself. . . . Further, genius consists in the working of the free intellect., and as a consequence the productions of genius serve no useful purpose. The work of genius may be music, philosophy, painting, or poetry; it is nothing for use or profit. To be useless and unprofitable is one of the characteristics of genius; it is their patent of nobility.
If a man sets out to hate all the miserable creatures he meets, he will not have much energy left for anything else; whereas he can despise them, one and all, with the greatest ease.
alent is like the marksman who hits a target which others cannot reach; genius is like the marksman who hits a target, as far as which others cannot even see.