Surely it must be plain that an ingenious man could speculate without end on both sides, and find analogies for all his dreams. Nor does it help me to tell me that the aspirations of mankind

Science is simply common sense at its best.

If a little knowledge is dangerous, where is the man who has so much as to be out of danger?

Living things have no inertia, and tend to no equilibrium.

I do not say think as I think, but think in my way. Fear no shadows, least of all in that great spectre of personal unhappiness which binds half the world to orthodoxy.

It is not what we believe, but why we believe it. Moral responsibility lies in diligently weighing the evidence. We must actively doubt; we have to scrutinize our views, not take them on trust. No virtue attached to blindly accepting orthodoxy, however 'venerable'.

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.