The long summer was over. For ages a tropical climate had prevailed over a great part of the earth, and animals whose home is now beneath the Equator roamed over the world from the far South to the very borders of the Arctics ... But their reign was over. A sudden intense winter, that was also to last for ages, fell upon our globe.

The time has come when scientific truth must cease to be the property of the few, when it must be woven into the common life of the world.

You cannot do without one specialty. You must have some base-line to measure the work and attainments of others. For a general view of the subject, study the history of the sciences. Broad knowledge of all Nature has been the possession of no naturalist except Humboldt, and general relations constituted his specialty.

Select such subjects that your pupils cannot walk out without seeing them. Train your pupils to be observers, and have them provided with the specimens about which you speak. If you can find nothing better, take a house-fly or a cricket, and let each one hold a specimen and examine it as you talk.

The surface of the earth is not simply a stage on which the thousands of present and past inhabitants played their parts in turn. There are much more intimate relations between the earth and the living organisms which populated it, and it may even be demonstrated that the earth was developed because of them.

The office of science is not to record possibilities; but to ascertain what nature does ... As far as Darwinism deals with mere arguments of possibilities or even probabilities, without a basis of fact, it departs from the true scientific method and injures science, as most of the devotees of the new ism have already done.

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