The Four states of matter and their corresponding evolutes may be thus figured— [Illustration: Figure 3.] In a subsequent section we may profitably consider the analogy existing between the cosmical and anthropological evolutions, and the consequent relations of the human soul with the planet to which it is related in the scheme of things. CHAPTER VII READING THE SYMBOLS The possibility of a scientific foreknowledge of events has long engaged the minds of speculative thinkers. In properly informed minds it has assumed an actuality. The learned writer of _The Story of the Heavens_ has given us a most interesting account of the manner in which the law of the Tides gradually came to be connected with the Moon, and how at length some astute observer formulated a scheme based on the Moon’s age, by which the time of high or low tide could be predicted. That was a case of scientific foreknowledge. When to the laws of Kepler, which gave a mathematical construction to the whole system of astronomy, Sir Isaac Newton contributed his great law of Gravitation, the coherence of the whole cosmical scheme was manifest. Kepler showed that planetary motions answered to the functions of the ellipse. Newton demonstrated the necessity of this cosmical fact. Herschel discovered the proper motion of the Sun in space and upset the whole scheme. Although answering to the functions of an ellipse, of which the stationary Sun occupied one of the foci, the necessary fact immediately assumed the less rigid form of relative fact, and the ellipse gave place to the cycloidal curve. A cycloidal curve is that described by any point on the tyre of a revolving wheel whose axle is progressing at the same time in a straight line. Let the Sun occupy the position of the axle, and let a planet be situate at the end of one of the spokes of the wheel upon the tyre. If the wheel be now moved forward it will be found that the Sun-point is moving in a straight line parallel to the ground on which the wheel rests, while the planet-point describes a series of arches. It never gets farther away from the centre to which it is united. The planet point, in fact, describes a segment of a circle the chord of which is equal to the circumference of the wheel. We are under no necessity of supposing that the Sun’s path in space is rectilinear. On the contrary, we have presumptive evidence that it is itself answering to the gravitational pull of some body in the remote confines of space and pursuing an orbital path. [Illustration: Figure 4. Diagram showing the Cycloidal curve of a planet on a vector S´-C, where A, C, B are the tropics. Then the straight line S-S´´ is equal to 2(S´C) × 3·14159.] We are here dealing with a rigid vector, which is not the case as regards the planetary bodies. There is a difference in nature between the spoke of a wheel that holds the tyre to the hub and the force of gravity that holds a planet to the Sun.