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

If an angel were to tell us about his philosophy, I believe many of his statements might well sound like '2 x 2= 13'.

How might letters be most efficiently copied so that the blind might read them with their fingers?

It is a sure evidence of a good book if it pleases us more and more as we grow older.

There is a great difference between believing in something and believing in it again.

Erudition can produce foliage without bearing fruit.

There is no more important rule of conduct in the world than this: attach yourself as much as you can to people who are abler than you and yet not so very different that you cannot understand them.