Everything has been thought of before, but the problem is to think of it again.
Progress has not followed a straight ascending line, but a spiral with rhythms of progress and retrogression, of evolution and dissolution.
Everybody wants to be somebody; nobody wants to grow.
Science and art belong to the whole world, and before them vanish the barriers of nationality.
Science has been seriously retarded by the study of what is not worth knowing, and what is not knowable.
The greatest difficulties lie where we are not looking for them.
Wisdom is only found in truth.
Man is not born to solve the problem of the universe, but to find out what he has to do; and to restrain himself within the limits of his comprehension.
It is easier to perceive error than to find truth, for the former lies on the surface and is easily seen, while the latter lies in the depth, where few are willing to search for it.
All truly wise thoughts have been thought already thousands of times; but to make them truly ours, we must think them over again honestly, till they take root in our personal experience. One always has time enough, if one will apply it well.
The deed is everything, the glory is naught.
Hatred is something peculiar. You will always find it strongest and most violent where there is the lowest degree of culture.
We do not understand we do not possess,