Page:Ferrier's Works Volume 3 "Philosophical Remains" (1883 ed.).djvu/446

436 and that these sensations (which have no more resemblance to the qualities of matter, than the words of a language have to the things they denote) are followed by a perception of the existence and qualities of the bodies by which the impressions are made; that all the steps of this process are equally incomprehensible." There are at least two points which are well worthy of being attended to in this quotation. First, Mr Stewart says that Reid "exhibited the difficulty of the problem of perception, in all its magnitude, by a plain statement of fact." What does that mean? It means this: that Reid stated, indeed, the fact correctly, namely, that external objects give rise to sensations and perceptions, but that still his statement did not penetrate to the heart of the business, but, by his own admission, left the difficulty undiminished. What difficulty? The difficulty as to how external objects give rise to sensations and perceptions. Reid did not undertake to settle that point—a wise declinature, in the estimation of Mr Stewart. Now Mr Stewart, understanding, as he did, the philosophy of causation, ought to have known that every difficulty as to how one thing gives rise to another, is purely a difficulty of the mind's creation, and not of nature's making, and is, therefore, no difficulty at all. Let us explain this. A man says he knows that fire explodes gunpowder; but he does not know how or by what means it does this. Suppose, then, he finds out the