Of all the inventions of man I doubt whether any was more easily accomplished than that of a Heaven.

Man…who lives in three places – in the past, in the present, and in the future – can be unhappy if one of these three is worthless. Religion has even added a fourth – eternity.

Man loves company - even if it is only that of a small burning candle.

What we have to discover for ourselves leaves behind in our mind a pathway that can be used on another occasion.

Once we know our weaknesses they cease to do us any harm.

First there is a time when we believe everything, then for a little while we believe with discrimination, then we believe nothing whatever, and then we believe everything again - and, moreover, give reasons why we believe.

There is no greater impediment to progress in the sciences than the desire to see it take place too quickly.