The terms of this proposition differ but little from those in which argument is usually made in support of the reality of external objects, but with Dr. Mivart it serves as the text of a refutation of Mr. Spencer’s theory of “transfigured realism.” Mr. Spencer stoutly professes his belief in the realism of the external world, but distinguishes his conception of it from the common crude realism of the majority as having been by him filtered through the intellect, and based, not on the direct data of the senses, but on these as interpreted by the mind. According to him, “what we are conscious of as properties of matter, even down to its weight and resistance, are but subjective affections produced by objective agencies which are unknown and unknowable.” Divested of an involved and trying terminology, Mr. Spencer’s theory amounts to this: The mind under the experience of a sensation is irresistibly borne to admit that it is not itself the active agent concerned in its production; for sensation as a “passing state of consciousness” is not accompanied by that other “passing state of consciousness” which exhibits the mind to itself as spontaneously generating the sensation in question. Therefore that sensation is derived _ab extra_; therefore its cause, unknown or unknowable, is something outside of the mind――_i.e._, has an objective reality. It is a sort of game of blind man’s buff between the mind and the world, according to Mr. Spencer――we know something has impressed us, but how or what we cannot find out. “Thus the universe, as we know it,” says Dr. Mivart, “disappears not only from our gaze, but from our very thought. Not only the song of the nightingale, the brilliancy of the diamond, the perfume of the rose, and the savor of the peach lose for us all objective reality――these we might spare and live――but the solidity of the very ground we tread on, nay, even the coherence and integrity of our own material frame, dissolve from us, and leave us vaguely floating in an insensible ocean of unknown potentiality.” This is “transfigured realism” with a vengeance, and leaves us somewhat at a loss to know what can be meant by idealism. It practically differs not from the doctrine of Berkeley and Hume; for it matters little to us whether external objects exist or not, if they are in and by themselves something “unknown and unknowable,” altogether different from what we consider them to be. The radical fault of Mr. Spencer’s “transfigured realism” is that he mistakes sensations themselves for the act of the mind which is concerned about them; and when in reality he speaks merely of the sensations as such, he imagines he has in view purely speculative intellectual acts. Such confusion is quite natural in a philosopher who recognizes no form of idea but transformed sensation, no purely unimaginable conceivability. This is evident when he says: