man down to the lowest radiate, and upon this as absciss we erect ordinates representing the degrees of intelligence, then by connecting these ordinates we develop what might be called the line of intelligence. This line, as is seen, rapidly descends from the higher to the lower races of man, then makes a sudden fall from the lowest races of men to the highest species of monkeys, and thence gradually descends until the ordinates of intelligence become insensible, though they probably still exist down to the lowest point, b. If in a similar way we construct a line of instinct, it would probably rise as we pass down through the lower races of men and through the animal scale, reaching its maximum about the middle of the series among insects, and again declining to the end. If, however, we were to construct a third line representing the relative amounts of these two, i. e., the proportion of instinct to intelligence, it would probably be a continuously rising curve something like the dotted line in the diagram. The quotient of instinct divided by intelligence, of acquired wisdom divided by inherited wisdom, constantly increases as we go down the scale.
Such, then, is the nature of instinct, and such its general relations to intelligence. But the most important question still remains. How was this wondrous faculty acquired? Whence did it come? How is it derived? In a word, what is the true theory of the origin of instinct?
The Origin of Instinct.—The old theology disposes of the above question, as she does so many others, in the most summary way. According to her, instincts are not acquired or derived at all. They are miraculously given in perfection to the first individuals of the species, to each species its several kind. But this explanation cannot satisfy Science. It simply places the question beyond her domain..To science Nature is a continuous chain, and her mission is to recover every link. To her a true explanation of any phenomenon consists in connecting it with other phenomena most nearly allied to it. A scientific explanation or theory of instinct must connect it with intelligence on the one hand and the lower phenomena of the nervous system on the other—must show how all these several capacities are evolved the one from the other—must bring them all under the universal law of evolution.
This, it is admitted, is no easy task. The wonderful instincts of some animals have always been regarded as one of the greatest objections to the theory of evolution. The origin of instinct is reckoned one of the hardest nuts for evolutionists to crack. The subject is indeed an obscure one, but recently some light begins to break. The task is indeed a hard one, but I believe we begin to understand in what direction, at least, we must work. The question is yet far from solved—we are yet in much perplexity, but I think we hold the thread which must eventually lead us out of this labyrinth! I have thought much for many years on this subject, and I now give you the views
