In all these assaults on the senses there is a great wisdom — not only about the addictiveness of pleasures but about their ephemerality. The essence of addiction, after all, is that pleasure tends to desperate and leave the mind agitated, hungry for more. The idea that just one more dollar, one more dalliance, one more rung on the ladder will leave us feeling sated reflects a misunderstanding about human nature — a misunderstanding, moreover, that is built into human nature; we are designed to feel that the next great goal will bring bliss, and the bliss is designed to evaporate shortly after we get there. Natural selection has a malicious sense of humor; it leads us along with a series of promises and then keeps saying ‘Just kidding.’ As the Bible puts it, ‘All the labour of man is for his mouth, and yet the appetite is not filled.’ Remarkably, we go our whole lives without ever really catching on.The advice of the sages — that we refuse to play this game — is nothing less than an incitement to mutiny, to rebel against our creator. Sensual pleasures are the whip natural selection uses to control us to keep us in the thrall of its warped value system. To cultivate some indifference to them is one plausible route to liberation. While few of us can claim to have traveled far on this route, the proliferation of this scriptural advice suggests it has been followed some distance with some success.
The flesh resists this daily humiliation, first by a frontal attack, and later by hiding itself under the words of the spirit (i.e. in the name of 'evangelical liberty'). We claim liberty from all legal compulsion, from self-martyrdom and mortification, and play this off against the proper evangelical use of discipline and asceticism; we thus excuse our self-indulgence and irregularity in prayer, in meditation and in our bodily life. But the contrast between our behavior and the word of Jesus is all too painfully evident. We forget that discipleship means estrangement from the world, and we forget the real joy and freedom which are the outcome of a devout rule of life. As soon as a Christian recognizes that he has failed in his service, that his readiness has become feeble, and that he has sinned against another's life and become guilty of another's guilt, that all his joy in God has vanished and that his capacity for prayer has quite gone, it is high time for him to launch an assault upon the flesh, and prepare for better service by fasting and prayer (Luke 2:37; 4:2: Mark 9:29; 1 Cor. 7:5).