Subsequent to that time I have always been interested by these great tangles. Seeing them as in New York facing river banks where ships await their cargoes, or surrounded by the tall coal pockets and grain elevators of a crowded commercial section, I have often thought how typical of the shift and change of life they are, how peculiarly of this day and no other. Imagine a Roman, a Greek, an Egyptian or an Assyrian being shown one of these immense freight yards with their confusing mass of cars, their engines, bells, spirals of smoke and steam, their interesting variety of color, form and movement. How impossible to explain to such an one the mechanism if not the meaning of it all. How impossible it would be for him to identify what he saw with anything that he knew. The mysterious engines, the tireless switching, the lights, the bells, the vehicles, the trainmen and officials. And as far as some future age that yet may be is concerned, all that one sees here or that relates to this form of transportation may even in the course of a few hundred years have vanished as completely as have the old caravanseries of the Orient--rails, cars, engines, coal and smoke and steam, even the intricate processes by which present freight exchange is effected. And something entirely different may have come in its place, transportation by air, for instance, the very mechanism of flight and carriage directed by wireless from given centers. [Illustration: The Car Yard] And yet, as far as life itself is concerned, its strife and change, how typical of it are these present great yards with their unending evidences of movement and change. These cars that come and go, how heavy now with freight, or import; how empty now of anything suggesting service or use even, standing like idle, unneeded persons upon some desolate track, while the thunder of life and exchange passes far to one side. And anon, as in life, each and every one of them finds itself in the very thick of life, thundering along iron rails from city to city, themselves, or rather their contents, eagerly awaited and welcomed and sought after, and again left, as before. And then the old cars, battered and sway-backed by time and the elements and long service, standing here and there unused and useless, their chassis bent and sometimes cracked by undue strain or rust, their sides bulging, their roofs and doors decayed and warped or broken, quite ready for that limbo of old cars, the junk yard rather than the repair shop.