Just as the troubled regions which lie below the sphere of the moon are contrasted with the serene heaven which incloses and limits them, so the changing forms of matter which compose our globe and its nearer surroundings are contrasted with the simple unalterable substance of the heavenly spheres. "Of necessity," says Aristotle, "there exists a simple body whose very nature it is to be borne on in circular motion."[329] Elsewhere he says that the men of old "would seem to have assumed that the body which moves forever is likewise divine by nature."[330] This is "an embodied substance different from the compounds here, more divine and prior to them all";[331] a body "of a nature the more precious the farther it is withdrawn from what is here."[332] After reasoning about this body Aristotle says:—
"If what has been laid down be accepted, it is plain from the foregoing why the first of bodies is eternal, and shows neither growth nor decay nor old age nor alteration, and is affected by nothing. The conception seems to testify to the phenomena and the phenomena to the conception.... Therefore, as the first body is something different from earth and fire and air and water, [the ancients] gave the name of ether to the region most on high, naming it from its moving always during all eternity."[333]
The place in nature of "the first element," so grandly conceived, is fixed more definitely by Aristotle when he says "that the whole universe in the region of the courses on high is filled with that body."[334]
Now, therefore, we have attained the object of our rapid quest; at last we have reached "the element of the stars"; for Aristotle tells us that not only heaven, but all the heavenly bodies as well, consist of the ether, saying:—
"It is most reasonable and consequent, in view of things already said, for us to make each of the stars out of that body in which it has its course, since we have declared the existence of something of which the nature is to be borne in a circle."[335]
At a later day the ethereal element of the stars was distinguished from the four inferior elements not by its Aristotelian name of first element but by that of fifth element, or fifth existence, or fifth "essence." Hence arose and was applied to the fifth element the name "quintessence"; a word which in its turn acquired various meanings.
Ten years after Harvey's death Milton published his description of the creation of heaven; a description couched, however, in terms of the uncreated heaven of Aristotle. Milton wrote:—
"And this ethereal quintessence of heaven
Flew upward, spirited with various forms,
That roll'd orbicular, and turned to stars
Numberless, as thou seest, and how they move;
Each had his place appointed, each his course;
The rest in circuit walls this universe."[336]
We may now return from this excursion through the "Cosmos," to bring its light to bear upon those high-sounding words of Aristotle which, according to Harvey, formed the basis of speculations about the innate heat, the spirits, and the blood, which were handed down by "Scaliger, Fernelius, and others," and affected the views of Harvey himself. Aristotle had written:—
"The virtue or potency of every soul[316] seems to be associated with a body[317] other than the so-called elements, and more divine."