When the body’s perception is sound, one is aware of what sickness afflicts it, while if one is not aware one is a victim of obtuseness. Similarly the intellect, as long as it preserves its own proper energy, is conscious of its powers and knows from where the tyrannizing passions enter it; and it makes a determined stand against them. But it is terrible to pass ones days in a state of oblivion, like one who fights by night, not being able to see the evil thoughts against which one is battling.
-St Theodoros the Great Ascetic