I have mastered the principles of several religions. They have all shocked me by the violence which I should have to do to my reason to accept the dogmas of any one of them.

When the spirits are low, when the day appears dark, when work becomes monotonous, when hope hardly seems worth having, just mount a bicycle and go out for a spin down the road, without thought on anything but the ride you are taking.

What one man can invent, another can discover.

Our ideas must be as broad as Nature if they are to interpret Nature.

I am somewhat exhausted; I wonder how a battery feels when it pours electricity into a non-conductor?

But love is an emotional thing, and whatever is emotional is opposed to that true cold reason which I place above all things.

Education never ends, Watson. It is a series of lessons, with the greatest for the last.