The writer does not intend touching upon theories of the origin of the Universe, nor of its purpose, or of any design in its production or management, nor of its possible or probable end. These questions do not belong to our subject, and then again, as was said in the last chapter, speculation regarding it is devoid of results, and leads one to quicksands and bogs of mental reasoning, from which it is difficult to extract oneself. The answer to the Riddle of the Universe rests with The Infinite. But it is different with the case of the manifested Universe that is evidenced by our senses. Science is a different thing from metaphysics, and its process and mode of work are along different lines. And, much knowledge of Things may be obtained from a consideration of it--remembering always, that its knowledge is confined to Things, and not to That-which-is-back-of-Things. And, so let us consider the Universe of Things. Material Science has held that the Universe is composed of two principles, (1) Matter; (2) Energy or Force. Some hold that these two principles really are aspects of the same thing, and that there is really but one Principle, one aspect of which is shape, form, etc., and called Matter; the other a quality manifesting in Motion, which quality is called Force. Others, the most radical, hold that there is nothing but Matter, and that Force and Energy is but a "quality," or "power," inherent in Matter. Others hold that Force is the "real thing" and Matter but a form of Force. All branches hold to the idea that Matter and Energy are always found together, and can not be thought of separately. Matter and Force are held to be Eternal, and Infinite, it following that there can be no addition to, or subtraction from either; all apparent loss and gain, creation and destruction being but change of form or mode. God is declared unnecessary, and the Universe is held to operate according to certain Laws of Matter or Force (either or both) which are unchangeable and immutable--eternal and always valid. Mind and Thought are held to be products of properties of Matter or Force (one or both), secreted, evolved, or produced in the Brain. The Soul is relegated to the waste heap, and discarded as useless in the new philosophy. _Moleschott_ said, "Thought is a motion of Matter"; and _Holbach_, that "Matter enjoys the power of thinking." "Natural Laws" are held to be sufficient for the explanation of all phenomena, although ignoring the fact that the reason has never before formed the conception of a "law," without thinking it necessary to think of a "law-maker," or a power to enforce and administer the law. However, the philosophers hold that it is no more difficult to think of such a law than to try to form an idea of Space or Eternity, both of which are unthinkable to the human reason, but both of which are admitted as self-evident facts.