In practical life we are compelled to follow what is most probable ; in speculative thought we are compelled to follow truth.

He who has a true idea simultaneously knows that he has a true idea, and cannot doubt of the truth of the thing perceived.

Freedom is absolutely necessary for the progress in science and the liberal arts.

Those who wish to seek out the cause of miracles and to understand the things of nature as philosophers, and not to stare at them in astonishment like fools, are soon considered heretical and impious, and proclaimed as such by those whom the mob adores as the interpreters of nature and the gods. For these men know that, once ignorance is put aside, that wonderment would be taken away, which is the only means by which their authority is preserved.

You, dear reader, have now two accounts to choose between and there can be no doubt which is most probable.

Be not astonished at new ideas; for it is well known to you that a thing does not therefore cease to be true because it is not accepted by many. -Spinoza.