Does he, then, declare himself a materialist? A materialist is one who asserts everything which exists to be matter, or an affection of matter. What, then, is matter, and how is that to be defined? The common definition of matter is, that which is perceived by the senses, or the substance underlying sensible phenomena. By means of the senses we perceive such qualities or phenomena as resistance, form, color, perfume, sound. Whenever we observe these phenomena, whenever we see, hear, taste, touch, or smell, we attribute the affections thus excited to an external substance, which we call _matter_. But we are aware of other phenomena which are _not_ perceived by the senses,--- such as thought, love, and will. We are as certain of their existence as we are of sensible phenomena. I am as sure of the reality of love as I am of the whiteness of chalk. By a law of our mind, whenever we perceive sensible phenomena, we necessarily attribute them to a substance outside of ourselves, which we call matter. And by another law, or the same law, whenever we perceive the phenomena of consciousness, we necessarily attribute them to a substance which we call soul, mind, or spirit. All that we know of matter, and all that we know of soul, is their phenomena, and as these are entirely different, we are obliged to assume that matter and mind are different. None of the qualities or attributes of matter belong to mind, none of those of mind to matter. Does Tyndall deny this distinction? Apparently not. He not only makes Bishop Butler declare, with unanswerable power, that materialism can never show any connection between molecular processes and the phenomena of consciousness, but he distinctly iterates this in his own person at the end of the address; asserting that there is no fusion possible between the two classes of facts, those of sensation and those of consciousness. Professor Tyndall, then, in the famous sentence above quoted, does not declare himself a materialist in the only sense in which the term has hitherto been used. He does not pretend that sensation, thought, emotion, and will are reducible, in the last analysis, to solidity, extension, divisibility, etc.; he positively and absolutely denies this.