A person may cause evil to others not only by his actions but by his inaction, and in either case he is justly accountable to them for the injury.

So true is that unnatural generally means only uncustomary, and that everything which is usual appears natural.

However unwillingly a person who has a strong opinion may admit the possibility that his opinion may be false, he ought to be moved by the consideration that, however true it may be, if it is not fully, frequently, and fearlessly discussed, it will be held as a dead dogma, not a living truth.

It appears, then, to be a condition of a genuinely scientific hypothesis, that it be not destined always to remain an hypothesis, but be certain to be either proved or disproved by.. .comparison with observed facts.

Human beings are not like sheep; and even sheep are not undistinguishably alike. A man cannot get a coat or a pair oboots to fit him, unless they are either made to his measure, or he has a whole warehouseful to choose from: and is it easier to fit him with a life than with a coat, or are human beings more like one another in their whole physical and spiritual conformation than in the shape of their feet? If it were only that people have diversities of taste, that is reason enough for not attempting to shape them all after one model.

Among the works of man, which human life is rightly employed in perfecting, the first in importance surely is man himself.

The peculiarity of the evidence of mathematical truths is that all the argument is on one side.