One of the chief distinctions between man and animals is the faculty of language. Let us look at this for a moment. "The essential differences," says Prof. Whitney, "which separate man's means of communication in kind as well as degree from that of the other animals is that, while the latter is instinctive, the former is in all its parts arbitrary and conventional. No man can become possessed of any language without learning it; no animal (that we know of) has any expression which he learns, which is not the direct gift of nature to him." Any child of parents living in a foreign country grows up to speak the foreign speech, unless carefully guarded from doing so; or it speaks both this and the tongue of its parent with equal readiness. A child must learn to observe and distinguish before speech is possible, and every child begins to know things by their name before he begins to call them. "If it were not for the added push," says Prof. Whitney, "given by the desire of communication, the great and wonderful power of the human soul would never move in this particular direction; but when this leads the way, all the rest follows." No philologist now supposes that any language has been deliberately invented; it has been slowly and unconsciously developed by many steps. There can be no question that language owes its origin to the imitation and modification of various natural sounds, the voices of other animals, and man's own instinctive cries, aided by signs and gestures; and this is the opinion of Max Müller. And Prof. Whitney remarks that "spoken language began, we may say, when a cry of pain, formally wrung out by real suffering, and seen to be understood and sympathized with, was repeated in imitation, no longer as a mere instinctive utterance, but for the purpose of intimating to another." Darwin says that "the early progenitor of man probably first used his voice in producing true musical cadences, that is, in singing, as do some gibbon-apes at the present day. It is therefore probable that the imitation of musical cries by articulate sounds may have given rise to words expressive of very complex emotions."