given half as much thought to the nature of minds, for he was little interested in psychology. Nevertheless, his common sense—whatever that may be—led him to laugh at a way of looking at things that could not have struck Lucretius and many other able men as absurd at all.
It is extremely interesting to ask why the men of our day, I do not mean the professional psychologists, but the great mass of intelligent persons who do not care much for psychology, and who know little of philosophy, should take up certain ways of regarding things mental, and should unhesitatingly repudiate others which have once been popular. We can not in the least explain it by saying that their own experience of minds leads them to embrace such conclusions. As a rule, they do not reflect upon their experiences of their minds at all, and some of them are hardly capable of serious reflection upon the subject. As early as the seventeenth century, John Locke remarked that "the understanding, like the eye, whilst it makes us see and perceive all other things, takes no notice of itself; and it requires art and pains to set it at a distance, and make it its own object." To this modern psychologists will heartily subscribe.
The fact is that the average man's notions about the mind are a part of his share in the heritage of the race. He who knows something of the history of human thought finds in them the echoes of old philosophies—traces of theories sometimes the most fantastic. The common sense which guides men is the resultant attitude due to many influences, some of them dating very far back indeed.
I have said that, even among the ancient Greeks, there were protests against the materialization of the mind. Both Plato and Aristotle stood out against it, each in his own way. It is true that Plato distributes the soul through the body in a way that might strike an Epicurean as not unnatural—a part of it was below the diaphragm, a part of it in the chest, and a part of it in the head. But he does speak of this last and noblest part in somewhat the same tone as that in which men came later to speak of the human mind. Aristotle follows his teacher in regarding the reason, at least, as something to be carefully distinguished from everything material. However, it is interesting to note that he conceives of the divine reason, or first cause of motion, as touching the world without being touched by it.
May we not describe this last notion as material at one end, so to speak? If reason is so immaterial that it can not be touched by matter, what does it mean to say that it touches matter? But we must get used to queer ways of talking about minds, if we will follow the history of human thought. The seed dropped by Plato and Aristotle has grown into a tree when we come to Plotinus the Neo-Platonist, who lived in the third century after Christ.