Those theories in earlier times, which were professedly based on purely philosophical grounds, were most frequently of an extremely hypothetical character. Such were the speculations of most of the ancient philosophical sects ; they rather sought to make out some plausible system couched in the technical language of their schools, than fairly to trace what was really the order of nature, and follow by the humble but sure path of induction, the actual laws by which she is regulated, and which, when diligently studied, never fail to lead us on from one step of generalisation to another, until we arrive at the surest conviction of that universal order and profoundly-regulated unity and harmony of physical causes, which form the irresistible evidence of the all-pervading influence of the one great moral cause of the universe. We will, however, just mention one or two illustrative instances : Among the ancient philosophers, Plato distinctly ascribed the formation of all things to a supreme being, but seems also to have held the independent existence of matter ; that is, he maintained three principles—God, matter, idea : the idea being an incorporeal archetype existent in the divine mind, according to which matter was moulded and fashioned (Plutarch, De Piaci tis, i. 3.) This doctrine, indeed, seems to be nearly the same with that of Thales and Pythagoras, from whom it was probably borrowed. Cicero expressly tells us that ' Thales held water to be the principle of all rnings ; and God, that mind which fashioned all things out of water' (De Nat. Dear. i.) Aristotle held the pre-existence of matter ; and observes, 'It is the common opinion of naturalists that nothing can be made out of nothing ;' and that it is impossible that it should be otherwise (Phys. i. 4. 8.) And further: 'neither can everything be made out of everything, but out of some subject fitted thereto ; as animals and plants out of their seed' (1. c. 9). Here, indeed, he seems to be approaching the argument of simple physical induction, the legitimate result of which ought to be to remind us of the proper boundaries of all physical argument, and to show that the question of the original constitution of matter is one which no such induction can ever solve. And though probably they did not view the subject in this philosophical light, yet some of the fathers of the Christian Church, in their discussions of these speculative questions, have expressed the truth in terms exactly harmonising with the most rigid modern philosophy. It is impossible,' says St. Chrysostom, ' for man's nature by curious inquiry to penetrate into the workmanship of God' (In Gen. X07. (3') and Lactantius observes, ' His works are seen with the eyes, but how he made them, the mind itself cannot see' (§ 2). There are those who condemn all such speculations as evincing but the empty presumption of human reason : but they do not perceive that the real fault lies, not in the use of reason, but in the Perversion of it ; not in trusting to its guidance, but in refusing its cautions, and arrogantly imagining that we can penetrate regions where the only safe path of induction is manifestly closed to us.
In modern times there have not been wanting those who have pursued cosmogonical speculations on what they con sidered purely philosophical grounds; though to the adherents of strict inductive science their philosophical character will appear to stand on no better ground than the reveries of the ancients. For the sake of those readers who may feel interested in such theories, we may just name some of the most celebrated of these authors :—Buffon, in his Histoire Naturelle ; Wolfe, in his Cosmologia; Holbach, in his Systeme de la Nature (incorrectly ascribed to hlirabaud or to Lagrange) ; and the disciples of Kant, as Hegel, Oken, and others, among whom the most prominent is J. Minter. As a specimen of the kind of speculation pursued, we may briefly state that his work, Ueber die Entschung- der Welt aus Nichts, is founded on the old maxim, ex nihilo nihil fit from whence he deduces the existence of an original governing power possessing omni presence and omniscience. But the production of a world could only take place in one of two ways, ' either in a pantheistical or a spiritual mode ;' that is, the original power might create a world of which he, or an emanation from him, is the all-pervading soul, or might part with portions of his own intelligence, which might animate portions of the creation. Muller adopts the second of these, and contends that this distribution of the divine intelligence is what produces duration or time : the continued existence of time is the evidence of the continuance of divine power.
This power (if we have the least idea of the author's meaning), by indefinite continuance alone, becomes con centrated, as it were, in some kind of effect, which produces, or at least brings together, a sort of original matter or ether, which subsequently undergoes changes owing to three principal forces or forms of power—attraction, repulsion, and inertia ; after which, rotation being communicated, worlds and systems may result. But as we cannot pretend to say that from any statements we have seen we can render the subject at all more intelligible, we must hope this specimen may suffice.
If we turn to the more strict and proper investigation of physical science, it will be important to inquire what amount of testimony with respect to the origin of the world they may be able to supply.
The science of astronomy has sometimes been appealed to as having reference to the probable origin and antiquity of the solar system; but on a closer examination the degree of evidence which it furnishes will be found little more than conjectural.
The most recent and complete investigations of the theory of gravitation have totally excluded all idea of the action of adventitious causes in sustaining or disturbing the system Its apparent irregularities have been all analysed and reduced to calculation, to system, and order, and shown to be, in fact, but portions of the exact regularity by which the whole fabric is sustained, and which recur in a perfectly determinate cycle through determinate periods, though some of them are of immense length.
All this does not, however, prove that the universe has existed through those immensely long periods ; astronomical science does not show us any commencement; but there is no evidence whatever at variance with it.
Observations on the motions of Encke's comet have disclosed the high probability of the existence of a certain extremely rare medium through the celestial space, which offers a certain resistance to that small comet, itself com posed of extremely rarified matter. This medium, or ether, must therefore oppose some resistance, however inexpressibly small, to the solid planets : and the result must be, in an inconceivably long period of time, that they will approach, and finally fall into the sun.
Astronomy, then, may point to the termination of the present order of things. It has been argued, as a sort of analogous presumption, that that which will have an end had also a beginning ; but this, considered in the light of evidence of creation, is surely far too slight and inconclusive to be of much value. Another argument has been some times dwelt on to which we must refer rather more par ticularly. This is what is termed the Nebular Hypothesis,' which may be thus very briefly explained : La Place suggested it (purely as an hypothesis), which might give a plausible representation from analogy of the origin of the motions of the solar system. In all parts of the heavens powerful telescopes show us star-like objects which are not, like the other stars, brilliant luminous points, but extended bodies of comparatively little lustre. These are called nebula', and manifestly appear to be in various stages of condensation, from great diffuseness up to actual stars, and many of them having within them points of greater bright ness. La Place perceived an analogy between these and the solar system : he conceived that our whole system was once in the state of a nebula ; that it has undergone gradual condensation, the sun being the central star ; and that in this process each of the planets also formed a distinct centre of condensation, while in and by the process their respective motions were communicated to them, supposing the whole mass to have had originally impressed upon it a general rotatory motion, without which, and the centrifugal force resulting, all its particles must at once have been attracted together into one central mass. Thus other planetary masses would be found revolving round that centre at different distances. As the cooling and consequent con densation advanced, similar effects on a smaller scale would take place in each of those planetary masses, until they formed solid planets accompanied by rings or satellites. The resulting motions would be orbits not much differing from circles, and in planes not greatly inclined to each other, which accords generally well enough with the actual constitution of the solar system.