It basically means being purged from the desire for sensual or carnal pleasures. It doesn’t necessarily mean that you have to fast or throw out your x-box or spend all your day in church. What John is speaking about is attachment to these things. As St Benedict says “prefer nothing to the love of Christ.” John is saying the same thing. They way to union with God is through purgation of desires for carnal things. He calls these “disordered appetites.” Purgation is achieved in two dimension; the first is the purgation of the senses. It mean denying yourself the gratification of the “appetites.” So if you derive a lot of pleasure out of eating, perhaps you do need to fast. But if eating is just what you need to do to keep healthy and and you get an occasional joy out of a ice cream sundae or a dinner out, but your overall attachment to food is still in check, then you are OK. Eventually, as one progresses in the spiritual life, these carnal pleasures hold no attraction. But that is not the end. Then God takes over and one goes through spiritual purgation, which is purely the work of God and we can’t control that. Anyway that is how I see it from my reading of the Ascent.
