I hated tobacco. I could have almost lent my support to any institution that had for its object the putting of tobacco smokers to death...I now feel that smoking in moderation is a comfortable and laudable practice, and is productive of good. There is no more harm in a pipe than in a cup of tea. You may poison yourself by drinking too much green tea, and kill yourself by eating too many beefsteaks. For my part, I consider that tobacco, in moderation, is a sweetener and equalizer of the temper.

I really see no harm which can come of giving our children a little knowledge of physiology. ... The instruction must be real, based upon observation, eked out by good explanatory diagrams and models, and conveyed by a teacher whose own knowledge has been acquired by a study of the facts; and not the mere catechismal parrot-work which too often usurps the place of elementary teaching.

The rung of a ladder was never meant to rest upon, but only to hold a man's foot long enough to enable him to put the other somewhat higher.

Every philosophical thinker hails it [The Origin of Species] as a veritable Whitworth gun in the armoury of liberalism.

It is wrong for a man to say that he is certain of the objective truth of any proposition unless he can produce evidence which logically justifies that certainty.

Not only do I disbelieve in the need for compensation, but I believe that the seeking for rewards and punishments out of this lifeleads men to a ruinous ignorance of the fact that their inevitable rewards and punishments are here.

I have no faith, very little hope, and as much charity as I can afford.