The spherical bodies, on the other hand, have life, possess a soul by which they move spontaneously; they have no properties by which they could at any time come to a state of rest; in their perpetual rotations they are not subject to any change, except that of position. The question whether they are endowed with an intellect, enabling them to comprehend, cannot be solved without deep research. Through the constant revolution of the fifth element, with all contained therein, the four elements are forced to move and to change their respective positions, so that fire and air are driven into the water, and again these three elements enter the depth of the earth. Thus are the elements mixed together; and when they return to their respective places, parts of the earth, in quitting their places, move together with the water, the air and the fire. In this whole process the elements act and react upon each other. The elements intermixed, are then combined, and form at first various kinds of vapours; afterwards the several kinds of minerals, every species of plants, and many species of living beings, according to the relative proportion of the constituent parts. All transient beings have their origin in the elements, into which again they resolve when their existence comes to an end. The elements themselves are subject to being transformed from one into another; for although one substance is common to all, substance without form is in reality impossible, just as the physical form of these transient beings cannot exist without substance. The formation and the dissolution of the elements, together with the things composed of them, and resolving into them, follow each other in rotation. The changes of the finite substance, in successively receiving one form after the other, may therefore be compared to the revolution of the sphere in space, when each part of the sphere periodically reappears in the same position. As the human body consists both of principal organs and of other members which depend on them and cannot exist without the control of those organs, so does the universe consist both of principal parts, viz., the quintessence, which encompasses the four elements and of other parts which are subordinated and require a leader, viz., the four elements and the things composed of them. Again, the principal part in the human body, namely, the heart, is in constant motion, and is the source of every motion noticed in the body; it rules over the other members, and communicates to them through its own pulsations the force required for their functions. The outermost sphere by its motion rules in a similar way over all other parts of the universe, and supplies all things with their special properties. Every motion in the universe has thus its origin in the motion of that sphere; and the soul of every animated being derives its origin from the soul of that same sphere.