It is very rare to find people whose intelligence is in a state of stillness. Indeed, such a state is only to be found in those who through their whole manner of life strive to attract divine grace and blessing to themselves. If, then, we seek–by guarding our intellect and by inner watchfulness–to engage in the noetic work that is the true philosophy in Christ, we must begin by exercising self-control with regard to our food, eating and drinking as little as possible.
Watchfulness may fittingly be called a path leading both to the kingdom within us and to that which is to be; while noetic work, which trains and purifies the intellect and changes it from an impassioned state to a state of dispassion, is like a window full of light through which God looks, revealing Himself to the intellect.
~St Philotheos of Sinai
Prayerful Life 