Everyone admits that pain is educational:  Since I feel agony when I put my hand into the fire, I don’t do it again.  Curiously, we are much more reluctant to admit that there is such a thing as natural disgust, and disgust is educational too.  St. John Chrysostom makes this point exactly in his Homily on First Timothy:

“Food is called nourishment, to show that its design is not to injure the body, but to nourish it.  For this reason perhaps food passes into excrement, that we may not be lovers of luxury.  For if it were not so, if it were not useless and injurious to the body, we should not cease from devouring one another.  If the belly received as much as it pleased, digested it, and conveyed it to the body, we should see wars and battles innumerable.  Even now when part of our food passes into ordure, part into blood, part into spurious and useless phlegm, we are nevertheless so addicted to luxury, that we spend perhaps whole estates on a meal.  What should we not do, if this were not the end of luxury?  …

“Some have strangely complained, wondering why God has ordained that we should bear a load of ordure with us.  But they themselves increase the load.  God designed thus to detach us from luxury, and to persuade us not to attach ourselves to worldly things.”

The passage was called to my attention by my friend Daniel Mattson, who blogs at Letters to ChristopherI won’t say more about the passage here because I don’t want to encroach on Dan’s own insights about it, which he will be discussing in a book he is writing for Ignatius Press.