When these Dualistic philosophers are consistent they must assign a moment in the phylogeny of the human soul at which it was first "introduced" into man's vertebrate body. Hence, at the time when the human body was evolved from the anthropoid body of the ape (probably in the Tertiary period), a specific human psychic element--or, as people love to say, "a spark of divinity"--must have been suddenly infused or breathed into the anthropoid brain, and been associated with the ape-soul already present in it. I need not insist on the enormous theoretical difficulties of this idea. I will only point out that this "spark of divinity," which is supposed to distinguish the soul of man from that of the other animals, must be itself capable of development, and has, as a matter of fact, progressively developed in the course of human history. As a rule, reason is taken to be this "spark of divinity," and is supposed to be an exclusive possession of humanity. But comparative psychology shows us that it is quite impossible to set up this barrier between man and the brute. Either we take the word "reason" in the wider sense, and then it is found in the higher mammals (ape, dog, elephant, horse) just as well as in most men; or else in the narrower sense, and then it is lacking in most men just as much as in the majority of animals. On the whole, we may still say of man's reason what Goethe's Mephistopheles said:-- Life somewhat better might content him But for the gleam of heavenly light that Thou hast given him. He calls it reason; thence his power's increased To be still beastlier than any beast.