The lower animals, on the other hand, must have their bodily structure modified in order to survive under greatly changed conditions. They must be rendered stronger, or acquire more effective teeth or claws, in order to defend themselves from new enemies; or they must be reduced in size so as to escape detection and danger. When they migrate into a colder climate they must become clothed with thicker fur, or have their constitutions altered. If they fail to be thus modified, they will cease to exist.

[Alexander von Humboldt was the] greatest scientific traveller who ever lived.

Nothing could have been worse for the development of my mind than Dr. Butler's school, as it was strictly classical, nothing else being taught, except a little ancient geography and history. The school as a means of education to me was simply a blank. During my whole life I have been singularly incapable of mastering any language. Especial attention was paid to versemaking, and this I could never do well. I had many friends, and got together a good collection of old verses, which by patching together, sometimes aided by other boys, I could work into any subject.

If I had my life to live over again, I would have made a rule to read some poetry and listen to some music at least once every week.

The young blush much more freely than the old but not during infancy, which is remarkable, as we know that infants at a very early age redden from passion.

Such simple instincts as bees making a beehive could be sufficient to overthrow my whole theory.

I long to set foot where no man has trod before.