[150] like those diseases which would creep over the whole body, if they were not checked by excision or cautery, and which would overrun and seize upon the whole composition of the body, not leaving a single part in a sound state; in like manner, unless discourse in accordance with philosophy did not, like a good physician, check the influx of appetite, all the affairs of life would of necessity be set in motion in a manner contrary to nature; for there is nothing exempt from such an affliction, nothing which can escape the dominion of passion, but, when once it has obtained immunity and license, it devours everything and becomes by itself everything in every part.