C. Because we know only that of which we can conceive, in the sense of forming an adequate mental image. We reply: (_a_) It is true that we know only that of which we can conceive, if by the term “conceive” we mean our distinguishing in thought the object known from all other objects. But, (_b_) The objection confounds conception with that which is merely its occasional accompaniment and help, namely, the picturing of the object by the imagination. In this sense, conceivability is not a final test of truth. (_c_) That the formation of a mental image is not essential to conception or knowledge, is plain when we remember that, as a matter of fact, we both conceive and know many things of which we cannot form a mental image of any sort that in the least corresponds to the reality; for example, force, cause, law, space, our own minds. So we may know God, though we cannot form an adequate mental image of him. The objection here refuted is expressed most clearly in the words of Herbert Spencer, First Principles, 25-36, 98—“The reality underlying appearances is totally and forever inconceivable by us.” Mansel, Prolegomena Logica, 77, 78 (_cf._ 26) suggests the source of this error in a wrong view of the nature of the concept: “The first distinguishing feature of a concept, viz.: that it cannot in itself be depicted to sense or imagination.” Porter, Human Intellect, 392 (see also 429, 656)—“The _concept_ is not a mental image”—only the _percept_ is. Lotze: “Color in general is not representable by any image; it looks neither green nor red, but has no look whatever.” The generic horse has no particular color, though the individual horse may be black, white, or bay. So Sir William Hamilton speaks of “the unpicturable notions of the intelligence.” Martineau, Religion and Materialism, 39, 40—“This doctrine of Nescience stands in exactly the same relation to causal power, whether you construe it as Material Force or as Divine Agency. Neither can be _observed_; one or the other must be _assumed_. If you admit to the category of knowledge only what we learn from observation, particular or generalized, then is Force unknown; if you extend the word to what is imported by the intellect itself into our cognitive acts, to make them such, then is God known.” Matter, ether, energy, protoplasm, organism, life,—no one of these can be portrayed to the imagination; yet Mr. Spencer deals with them as objects of Science. If these are not inscrutable, why should he regard the Power that gives unity to all things as inscrutable?