_Metaphysics, what._--Of the two grand departments of human knowledge--the science of matter and the science of mind--the former, comprising whatever relates to material phenomena, the science of nature, is known under the general name of _Physics_; the latter, the science of mind, is often designated by the corresponding term, neither very correct nor very fortunate, _Metaphysics_. This term is often used to include whatever does not properly fall under the class of Physics. In its strict sense, it does not include so much, but denotes properly the science of abstract truth; the science of being, in itself considered--apart from its particular accidents and properties--that which we now call Ontology. The term is commonly ascribed to Aristotle, but incorrectly. It originated with his followers. Several treatises of his relating to natural science having been collected and published, under the title [Greek: ta physika], other treatises on philosophical subjects were afterward arranged under the title [Greek: ta metaphysika], indicating their relation to the former, as proper to be read after the perusal of those. Hence the term came into use in the general sense, already spoken of, to denote whatever is not included under physics although originally employed with a much more limited meaning. _Mental Philosophy not properly Metaphysics._--Neither in its wider nor in its stricter sense does this term properly designate the science of mind. Mental Philosophy neither embraces every thing not included under physics, nor is it the science of abstract being. As one of the intellectual, in distinction from the physical sciences, it holds a place along with Logic--the science of the laws of human thought and reasoning; Ethics--the science of morals; Politics--the science of human organization and government; to which should be added Ontology--the science of pure being; all which are properly embraced under the term Metaphysics in its wider and popular sense. To designate the science of mind in distinction from these other sciences, some more definite term is required. The word _Psychology_ is now coming into use as such a term. _Mental Philosophy a Natural Science._--The science of mind, indeed, deserves in one aspect to be ranked among the _natural_ sciences. It is a science resting on experience, observation, and induction--a science of facts, phenomena and laws which regulate the same. That which is specifically its object of investigation--the human mind--is strictly a part, and most important part of _nature_, unless we exclude man himself from the world to which he belongs, and of which he is lord.