To believe is very dull. To doubt is intensely engrossing.

He is not only dull himself, he is the cause of dullness in others

My own business always bores me to death; I prefer other people's

The old believe everything; the middle aged suspect everything: the young know everything.

If you tried to doubt everything you would not get as far as doubting anything. The game of doubting itself presupposes certainty.

Scepticism is the beginning of Faith.