CHAPTER III. THE PRESENT PHYSICAL UNIVERSE. ... οἱ οὐρανοὶ ῥοιζηδὸν παρελεύσονται, στοιχεῖα δὲ καυσούμενα λυθήσονται, καὶ γῆ καὶ τὰ ἐν αὐτῇ ἔργα κατακαήσεται.—Πετρού Βʹ. γʹ. ‘The cloud-capp’d towers, the gorgeous palaces, The solemn temples, the great globe itself, Yea, all which it inherit, shall dissolve; And, like this insubstantial pageant, faded, Leave not a rack behind.’—SHAKESPEARE, _Tempest_. ‘All worldly shapes shall melt in gloom, The sun himself must die Before this mortal shall assume His immortality.’—CAMPBELL. 92. Having in the last chapter briefly indicated the nature of the proposition which we intend to bring forward, we must next study, as a preliminary to further discussion, what science tells us about the present physical universe: what are the general laws to which it is now subject; when and what must have been its beginning; when and what will be its inevitable end. We have been driven into becoming accustomed to the phrase, ‘the material universe,’ which is generally used in a sense absolutely identical with that which we have chosen as the title of this chapter. We shall soon see that the term is a very inapt one, inasmuch as matter is (though it may sound paradoxical to say so) the less important half of the material of the physical universe. In the present chapter we shall still further restrict ourselves by omitting, as far as possible, any reference to life (even in its lowest aspect), and we likewise defer to a future chapter our account of the more reasonable speculations which have been advanced with regard to the intimate structure of matter and ether. 93. It is only within the last thirty or forty years that there has gradually dawned upon the minds of scientific men the conviction that there is something besides matter or stuff in the physical universe, something which has at least as much claim as matter to recognition as an objective reality, though, of course, far less directly obvious to our senses as such, and therefore much later in being detected. So long as men spoke of light, heat, electricity, etc., as imponderables, they merely avoided or put aside the difficulty. When they attempted to rank them as matter,—heat, for instance, as caloric,—they at once fell into errors, from which a closer scrutiny of experimental results would assuredly have saved them. The idea of _substance_ or _stuff_ as necessary to objective existence very naturally arises from ordinary observations on matter; and as there could be little doubt of the physical reality of heat, light, etc., these were in early times at once set down as matter. Fire, in fact (including, it is to be presumed, everything which involved either heat or flame, real or apparent), was in early times one of the four so-called _elements_.