Love is blind, but marriage restores its sight.

All mathematical laws which we find in Nature are always suspect to me, in spite of their beauty. They give me no pleasure. They are merely auxiliaries. At close range it is all not true.

Be wary of passing the judgment: obscure. To find something obscure poses no difficult, elephants and poodles find many things obscure.

The more experiences and experiments accumulate in the exploration of nature, the more precarious the theories become. But it is not always good to discard them immediately on this account. For every hypothesis which once was sound was useful for thinking of previous phenomena in the proper interrelations and for keeping them in context. We ought to set down contradictory experiences separately, until enough have accumulated to make building a new structure worthwhile.

Never undertake anything for which you wouldn't have the courage to ask the blessings of heaven.

God created man in His own image, says the Bible; philosophers reverse the process: they create God in theirs.

One of the greatest creations of the human mind is the art of reviewing books without having read them.