Pythagoras, Plato, and Aristotle declare that the voice is incorporeal; for it is not the air that causes the voice, but the figure which compasseth the air and its superficies having received a stroke, give the voice. But every superficies of itself is incorporeal. It is true that it move with the body but itself it hath no body; as we observe in a staff that is bended, the matter only admits of an inflection, while the superficies doth not. According to the Stoics a voice is corporeal since everything that is an agent or operates is a body; a voice acts and operates, for we hear it and are sensible of it; for it falls and makes an impression on the ear, as a seal of a ring gives its similitude upon the wax. Besides, everything that creates a delight or injury is a body; harmonious music affects with delight, but discord is tiresome. And everything that moved is a body; and the voice moves, and having its illapse upon smooth places is reflected, as when a ball is cast against a wall it rebounds. A voice spoken in the Egyptian pyramids is so broken, that it gives four or five echoes. CHAPTER XXI. BY WHAT MEANS THE SOUL IS SENSIBLE, AND WHAT IS THE PRINCIPAL AND COMMANDING PART OF IT. The Stoics say that the highest part of the soul is the commanding part of it: this is the cause of sense, fancy, consents, and desires; and this we call the rational part. From this principal and commander there are produced seven parts of the soul, which are spread through the body, as the seven arms in a polypus. Of these seven parts, five are assigned to the senses, seeing, hearing, smelling, tasting, touching. Sight is a spirit which is extended from the commanding part of the eyes; hearing is that spirit which from the principle reacheth to the ears; smelling a spirit drawn from the principal to the nostrils; tasting a spirit extended from the principle to the tongue; touching is a spirit which from the principal is drawn to the extremity of those bodies which are obnoxious to a sensible touch. Of the rest, the one called the spermatical is a spirit which reacheth from the principal to the generating vessels; the other, which is the vocal and termed the voice, is a spirit extended from the principal to the throat, tongue, and other proper organs of speaking. And this principal part itself hath that place in our spherical head which God hath in the world. CHAPTER XXII. OF RESPIRATION OR BREATHING.