We cannot fathom the marvelous complexity of an organic being; but on the hypothesis here advanced this complexity is much increased. Each living creature must be looked at as a microcosm--a little universe, formed of a host of self-propagating organisms, inconceivably minute and as numerous as the stars in heaven.

The loss of these tastes [for poetry and music] is a loss of happiness, and may possibly be injurious to the intellect, and more probably to the moral character, by enfeebling the emotional part of our nature.

Freedom of thought is best promoted by the gradual illumination of men’s minds which follows from the advance of science.

We behold the face of nature bright with gladness.

The survival or preservation of certain favoured words in the struggle for existence is natural selection.

So great is the economy of nature, that most flowers which are fertilised by crepuscular or nocturnal insects emit their odour chiefly or exclusively in the evening.

There is no fundamental difference between man and animals in their ability to feel pleasure and pain, happiness, and misery.