7. The orifices of the cavities are not exposed until one cuts off the tops of the ears and removes the head [i.e. the base] from the heart. Once they are cut off, a pair of orifices for the two chambers is revealed. For the thick vein, running up from one, escapes our eye unless we dissect.
These are the springs of man's existence: from them spread throughout his body those rivers with which his mortal habitation is irrigated, those rivers which bring life to man as well, for if ever they dry up, then man dies.