8. Close by the origin of the blood-vessels certain soft and cavernous [04 `porous'] bodies enfold the heart. Although they are called `ears' they are not perforated as ears are, nor do they hear any sound. They are in fact the instruments by which nature catches the air - the creation, as I believe, of an excellent craftsman, who seeing that the heart would be a solid thing owing to the density of its material, and in consequence would have no attractive power, he equipped it with bellows, as smiths do their furnaces, with which the heart controls its respiration. Here is the evidence for my statement: you can see the heart pulsing in its entirety, while the ears have a separate movement of their own as they inflate and collapse.