No great achievement is possible without persistent work.

There is no need to worry about mere size. We do not necessarily respect a fat man more than a thin man. Sir Isaac Newton was very much smaller than a hippopotamus, but we do not on that account value him less.

We must be sceptical even of our scepticism.

Even when the experts all agree, they may well be mistaken.

...impregnation will be regarded in an entirely different manner, more in the light of a surgical operation, so that it will be thought not ladylike to have it performed in the natural manner.

Every man, wherever he goes, is encompassed by a cloud of comforting convictions, which move with him like flies on a summer day.

If everything has a cause, then God must have a cause. If there can be anything without a cause, it may just be the world as God.