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 than a much smaller amount if you have not thought it over for yourself.
Happiness belongs to those who are sufficient unto themselves. For all external sources of happiness and pleasure are, by their very nature, highly uncertain, precarious, ephemeral and subject to chance.
Compassion for animals is intimately associated with goodness of character, and it may be confidently asserted that he who is cruel to animals cannot be a good man.
Happiness of any given life is to be measured, not by its joys and pleasures, but by the extent to which it has been free from suffering-from positive evil.
To attain something desired is to discover how vain it is; and…though we live all our lives in expectation of better things, we often at the same time long regretfully for what is past. The present, on the other hand, is regarded as something quite temporary and serving only as the road to our goal. That is why most men discover when they look back on their life that they have the whole time been living ad interim, and are surprised to see that which they let go by so unregarded and unenjoyed was precisely their life, was precisely in expectation of which they lived.
I observed once to Goethe that when a friend is with us we do not think the same of him as when he is away. He replied, "Yes! because the absent friend is yourself, and he exists only in your head; whereas the friend who is present has an individuality of his own, and moves according to laws of his own, which cannot always be in accordance with those which you form for yourself.
Opinion is like a pendulum and obeys the same law. If it goes past the centre of gravity on one side, it must go a like distance on the other; and it is only after a certain time that it finds the true point at which it can remain at rest.