When God the Logos created human nature He did not make the senses susceptible either to pleasure or to pain; instead, He implanted in it a certain noetic capacity through which men could enjoy Him in an inexpressible way. By this capacity I mean the intellect’s natural longing for God. But on his creation the first man, through an initial movement towards sensible objects, transferred this longing to his senses, and through them began to experience pleasure in a way which is contrary to nature. Whereupon God in His providential care for our salvation implanted pain in us as a kind of chastising force; and so through pain the law of death was wisely rooted in the body, thus setting limits to the intellect’s manic longing, in a manner contrary to nature, towards sensible objects.
~St Maximos the Confessor
Prayerful Life 