It's as if we were children with no awareness of the existence of such things as gymnastics and medicine, and somebody saw this and exhorted us to take care of our bodies and reproached us, saying that it's shameful that we devote such care to cultivating wheat, barley, vines and all the other things which we work hard to acquire for the sake of the body, while we fail to discover any skill or other means of making the body itself as good as possible, even though such skills exist.