Every man is indeed bound to do what he can to promote the good of others, and a man who is of no use to anyone is strictly worthless.

Whenever anyone has offended me, I try to raise my soul so high that the offense cannot reach it.

The rainbow is such a remarkable phenomenon of nature, and its cause has been so meticulously sought after by inquiring minds throughout the ages, that I could not choose a more appropriate subject for demonstrating how, with the method I am using, we can arrive at knowledge not possessed at all by those whose writings are available to us.

For how do we know that the thoughts which occur in dreaming are false rather than those others which we experience when awake, since the former are often not less vivid and distinct than the latter?

I suppose therefore that all things I see are illusions; I believe that nothing has ever existed of everything my lying memory tells me. I think I have no senses. I believe that body, shape, extension, motion, location are functions. What is there then that can be taken as true? Perhaps only this one thing, that nothing at all is certain.

But possibly I am something more than I suppose myself to be.

In the matter of a difficult question it is more likely that the truth should have been discovered by the few than by the many.