You always admire what you really don't understand.

A friend to all is a friend to none

Judge a man by his questions rather than by his answers.

When you learn, teach, when you get, give.

Empty pockets never held anyone back. Only empty heads and empty hearts can do that.

There are no limitations to the mind except those we acknowledge.

He who conquers others is strong; he who conquers himself is mighty.

Obsession is the wellspring of genius and madness.

Nobody made a greater mistake than he who did nothing because he could do only a little.

To me, being an intellectual doesn't mean knowing about intellectual issues; it means taking pleasure in them.

Yes, I guess you could say I am a loner, but I feel more lonely in a crowed room with boring people than I feel on my own.

Nothing fixes a thing so intensely in the memory as the wish to forget it.

It was a melancholy secret that reality can arouse desires but never satisfy them.

If we do not lay out ourselves in the service of mankind whom should we serve?

Never ruin an apology with an excuse.

Thoughts without content are empty, intuitions without concepts are blind.

Things which matter most must never be at the mercy of things which matter least.

There is no question climate change is happening. The only arguable point is what part humans are playing in it.

An understanding of the natural world is a source of not only great curiosity, but great fulfilment.

To a wise and good man the whole earth is his fatherland.

A single lie destroys a whole reputation of integrity.