The population question is the real riddle of the sphinx, to which no political Oedipus has as yet found the answer. In view of the ravages of the terrible monster over-multiplication, all other riddle sink into insignificance.

Within the last fifty years, the extraordinary growth of every department of physical science has spread among us mental food of so nutritious and stimulating a character that a new ecdysis seems imminent.

God give me strength to face a fact though it slay me.

To a clear eye the smallest fact is a window through which the infinite may be seen.

Agnosticism is not properly described as a "negative" creed, nor indeed as a creed of any kind, except in so far as it expresses absolute faith in the validity of a principle which is as much ethical as intellectual.

The man of science has learned to believe in justification, not by faith, but by verification.

The only question which any wise man can ask himself, and which any honest man will ask himself, is whether a doctrine is true or false.