A smattering of everything is worth little. It is a fallacy to suppose that an encyclopaedic knowledge is desirable. The mind is made strong, not through much learning, but by the thorough possession of something.

But unless some great revolution in nature modifies the present relative level between land and sea, it may safely be maintained that the present outer reef is the final southern boundary of the North American continent.

A laboratory of natural history is a sanctuary where nothing profane should be tolerated. I feel less agony at improprieties in churches than in a scientific laboratory.

In Europe I have been accused of taking my scientific ideas from the Church. In America I have been called a heretic, because I will not let my church-going friends pat me on the head.

In-depth studies have an influence on general ideas, whereas theories, in turn, in order to maintain themselves, push their spectators to search for new evidence. The mind's activity that is maintained by the debates about these works, is probably the source of the greatest joys given to man to experience on Earth.

I sometimes hear preachers speak of the sad condition of men who live without God in the world, but a scientist who lives without God in the world seems to me worse off than ordinary men.

Embryology furnishes, also, the best measure of true affinities existing between animals.