new principle? In the former case the philosopher’s inference was merely founded upon the temporary imperfection of physical science. Now, biological science is making rapid progress; how do you know it will not undermine your position here also? Can any definite criterion of the immaterial be posited, or must we retreat step by step as the biologist advances, at each step betraying the weakness of our logic? Remember that the last step is the spirituality of the human soul.
For many years it seemed to me that such a criterion was available. The properties of mind are very different from those of matter. If we are logical, and if we remember a little controversial history, we shall not infer forthwith that mind must be the manifestation of spirit, not an outgrowth of matter. But if we can show that the properties of mind are not merely different, but contradictory, entirely opposed to those of matter, we may defy the progress of the Materialist. No addition of non-entities will produce a being (except in the brain of a Hegel), no multiplication of ciphers will give a number. Now, consciousness itself is not a phenomenon of this character. There is, indeed, a vast gulf between the movements of the molecules of the brain and the states of consciousness which accompany them; but we have no satisfactory reason for asserting that the gulf will never be traversed. No Theist will deny that matter could have been endowed with consciousness, like Leibnitz’s monads, if the Creator so willed; in point of fact, unorganized matter is not, but it is strange to infer that, therefore, organized matter cannot be the subject of consciousness. When the new science of psycho-physics had pursued its investigations into the relation between cerebral changes and states of consciousness for a considerable time, and when the comparative anatomy of the nervous system has made equal progress, perhaps the problem will wear a different aspect. However that may be, it is not proved that consciousness may not have arisen from an improved nervous structure, and until that is done it is unlawful to introduce a new, immaterial element into animal nature. The history of the past and the elementary rules of logic forbid it.
As we ascend the scale of the animal kingdom, mere consciousness, irritability, takes the form of definite perception of external objects. We are justified (in spite of Cartesians) in attributing sensitive perceptions like our own to the higher classes of animals at least. Now, it appeared to me that sensation was the rock which would mark the limit of progress and Materialism. It mattered little whether we could say precisely where definite sensitive perception began or not; wherever it began, we had the impassable frontier of the immaterial world. There seemed to be an indivisibility in the perceptive principle which clearly precluded the possibility of its being material, for matter is as clearly compound and divisible. We perceive an object whole and
