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.

If I go for the alternative which is false, then obviously I shall be in error; if I take the other side, then it is by... chance that I arrive at the truth, and I shall still be at fault.... In this incorrect use of free will may be found the privation which constitutes the essence of error.

For each of us there is a set limit to our intellectual powers which we cannot pass.

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.

I accept no principles of physics which are not also accepted in mathematics.

We never understand a thing so well,and make it our own, as when we have discovered it for ourselves.

By 'God', I understand, a substance which is infinite, independent, supremely intelligent, supremely powerful, and which created both myself and everything else [...] that exists. All these attributes are such that, the more carefully I concentrate on them, the less possible it seems that they could have originated from me alone. So, from what has been said it must be concluded that God necessarily exists.