Science is the topography of ignorance. From a few elevated points we triangulate vast spaces, inclosing infinite unknown details. We cast the lead, and draw up a little sand from abysses we may never reach with our dredges.

Every man is an omnibus in which his ancestors ride.

The man of action has the present, but the thinker controls the future.

To be master of any branch of knowledge, you must master those which lie next to it, and thus to know anything you must know all.

But the moment you turn a corner you see another straight stretch ahead and there comes some further challenge to your ambition.

Be willing to commit yourself to a course, perhaps a long and hard one, without being able to foresee exactly where you will come out.

Life is an end in itself, and the only question as to whether it is worth living is whether you have had enough of it.