It is the same all over the world.  Stanley cut a track through the endless African forests.  But it lay between the Pygmy villages, along the paths they had made, and through the glades where they fought their battles with the storks.

Sometimes the first road is a river—­the track is already cut.  Try to find out where the settlements in America were in the very early days—­before 1800.  You will find them along the Hudson, the Juanita, the St. Lawrence, the James, the Mississippi Rivers.  But when these are left, men follow the squirrel-tracks and bear-tracks, or the paths of hunters, or the roads of Roman soldiers.  It is a standing puzzle to little children why all the great rivers flow past the great towns. (Why do they?) The answer to that question will tell you why the great battles are fought in the same regions; why Egypt has been the coveted prize of a dozen different conquerors (it is the gateway of the East); why our Civil War turned on the possession of the Mississippi River.  It is the roadways we fight for, the ways in and out, whether they be land or water.  Of course, we really fought for something better than the mere possession of a roadway, but to get what we fought for we had to have the roadway first.

The great principle at the bottom of everything in Nature is that the fittest survives:  or, as I think it is better to say it, in any particular conflict or struggle that thing survives which is the fittest to survive in this particular struggle.  This is Mr. Darwin’s discovery,—­or one of them,—­and the struggle for existence is a part of the great struggle of the whole universe, and the laws of it make up the methods of Evolution—­of Development.

It is clear now, is it not, how the railway route is the direct descendant of the tiny squirrel track between two oaks?  The process of development we call Evolution, and you can trace it all around you.  Why are your skates shaped in a certain way?  Why is your gun rifled?  Why have soldiers two sets of (now) useless buttons on the skirts of their coats? (I will give you three guesses for this, and the hint that you must think of cavalry soldiers.) Why are eagles’ wings of just the size that they are?  These and millions of like questions are to be answered by referring to the principle of development.

Sometimes it is hard to find the clew.  Sometimes the development has gone so far, and the final product has become so complex and special, that it takes a good deal of thinking to find out the real reasons.  But they can be found, whether they relate to a fashion, to one of the laws of our country, or to the colors on a butterfly’s wing.

There is a little piece of verse intended to be comic, which, on the contrary, is really serious and philosophical, if you understand it.  Learn it by heart, and apply it to all kinds and conditions of things, and see if it does not help you to explain them to yourself....