This earth was unintelligible to the Greeks, they looked upon it as a solitary being, without a peer in the whole universe; to us it is a planet; one of many, all governed by the same laws, all moving round the same centre. It is the same with man who also remained a riddle to the ancients. An intelligent study of the world’s history, which they knew but imperfectly, has enriched our language with a word which never passed the lips of Socrates, Plato or Aristotle--humanity. Where the Greeks saw barbarians, that is, human beings other than themselves--we see brethren; those whom they called heroes and demi-gods are our ancestors; those who appeared to them strangers, united by no ties, are to us one family in work and suffering, divided by language and severed by national enmity, but pressing forward step by step almost unconsciously towards the fulfilment of that inscrutable purpose for which the world was created. As we have ceased to see in nature the working of demons or the manifestation of an evil principle, so we deny in history an atomistic conglomerate of chances, or the despotic rule of a mute fate; we turn over the leaves of the past seeking for a hidden train of thought in the actions of the human race; we understand that every effect has its cause; that connecting links run through the moral world, as well as the physical world; that there is nothing irrational in either history or nature, and we believe that the human mind is called upon to discover in both the manifestations of a Divine Power, the source of our existence.[10] This result, however, we could not have attained without first recognising the fact that man is no isolated being, complete in himself; that if he is to be effectively studied he cannot be disassociated from his family, all the members of which are governed by the same laws, all move round the same centre, and all receive their light from the same focal point. He is one of a class, of one genus or kind, whom it would be impossible to estimate correctly, if we set aside his relations to his fellows. “To understand man,” an illustrious naturalist has said recently, “it is not sufficient _not_ to separate him from those whom he resembles in every point; it is quite as necessary to study him in connection with those closely related to him, the inferior animals.” Hitherto I have not mentioned a hypothesis which has been promulgated in our days on the origin of man, which would have been considered the most remarkable this century had seen, had it not appeared simultaneously with another treatment of a like subject equally noticeable for its profundity in another direction.