and still higher orders, and through various molar forms as crystals, rocks, cells, phytons, plants, organs and animals and on into stars and systems of stars, each embodiment appropriates a part of the motion of its several particles or atoms. The molecules of the lowest orders have their motions, the molecules of the second order have their motions, the cell and the crystal have their motions, the earth has its motion and the stellar system has its motion.
The speed of every particle of matter is the sum of all the speeds of the bodies in which it is incorporated. Speed can never be increased or diminished in an ultimate particle; it may be increased or diminished in any one of its embodiments, but only by deflecting the motions in its other embodiments. This point is vital to a clear comprehension of the philosophy of science and is worthy of further illustration from the fact that it becomes necessary to rid ourselves of an illusion of sense. I see a bird perched upon a tree, then I see it flying through the air to perch upon another tree. The bird seems to have motion between the trees which it did not seem to have while perched on the one or the other; but the molecules of the bird before the flight had the motion of vitality, and in moving from tree to tree the trajectory of these multifarious minute motions are all deflected. The millions of millions of molecular motions had their trajectories changed. The bird itself was moving with the earth about its axis and with the earth about the sun, and with the sun about a point in Hercules. This is its astronomical motion. The change in the trajectory of the millions of millions of molecules was only the equivalent of the change in the trajectory of the astronomical
