Books are the money of Literature, but only the counters of Science.

Men can intoxicate themselves with ideas as effectually as with alcohol or with bang and produce, be dint of serious thinking, mental conditions hardly distinguishable from monomania.

Science is organized common sense where many a beautiful theory was killed by an ugly fact.

The question of all questions for humanity, the problem which lies behind all others and is more interesting than any of them, is that of the determination of man's place in nature and his relation to the cosmos.

Each such answer to the great question, invariably asserted by the followers of its propounder, if not by himself, to be complete and final, remains in high authority and esteem, it may be for one century, or it may be for twenty: but, as invariably, Time proves each reply to have been a mere approximation to the truth tolerable chiefly on account of the ignorance of those by whom it was accepted, and wholly intolerable when tested by the larger knowledge of their successors.

Whatever evil voices may rage, Science, secure among the powers that are eternal, will do her work and be blessed.

I believe that history might be, and ought to be, taught in a new fashion so as to make the meaning of it as a process of evolution intelligible to the young.