Everyone is a genius at least once a year. The real geniuses simply have their bright ideas closer together.

Perhaps in time the so-called Dark Ages will be thought of as including our own.

I cannot say whether things will get better if we change; what I can say is they must change if they are to get better.

Nothing is more conducive to peace of mind than not having any opinion at all.

When a book and a head collide and there is a hollow sound, is it always from the book?

A book is a mirror; if an ass peers into it, you can not expect an apostle to peer out.

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.

One must judge men not by their opinions, but by what their opinions have made of them.

Failure is simply the opportunity to begin again, this time more intelligently.