Every phenomenon therefore whether physical or mental, is probably connected in an indissoluble manner with some preceding phenomenon, either immediately in point of time, or remotely through some static condition, usually that of stored up power. In this sense the great principle of continuity of phenomena appears to be universal, and the present state of the Universe is said to implicitly or potentially contain all the future states of the Universe. Mind also in this way, like each of the physical forces, often acts as a link in an endless chain of causes and effects, and is connected with non-mental phenomena in accordance with the great principles of science. Science has demonstrated what has been termed the "Convertibility of Forces," or, that when one form of energy disappears, another form (or forms) of energy, and in precisely equivalent amount, is produced in its stead, either in a latent or active state. The equivalent quantities of the various forms of {107} energy have also been discovered by actual experiment and measurement. A pound weight falling through 772 feet gives forth as much energy as would (in the form of heat) raise the temperature of one pound of water one Fahrenheit degree. We know that so much mechanical power is equal also to so much electric current, chemical action, &c., and a large amount of evidence exists to show that these transformations of energy occur in all the organs of living creatures, and in obedience to the law of their equivalents. How far mental power is a "mode of energy" transformable, and obedient to the laws of equivalence, are interesting questions for future research.