On Illness
The body is a slave and the soul is a queen; and therefore it is often also an act of God’s mercy when the body is worn down by illness, for through this the passions are weakened, and a person comes to his senses—and bodily illness itself sometimes arises from the passions.
Take away sin, and illnesses will depart—for they come upon us from sin, as Saint Basil the Great affirms: “Where do diseases come from? Where do bodily afflictions come from? The Lord created the body, not disease; the soul, not sin. And what is most beneficial and necessary? Union with God and communion with Him through love. Losing this love, we fall away from Him; and falling away, we become subject to various and manifold diseases” (“Homily on the Fact that God Is Not the Author of Evils”).
Headache comes from mental activity that is restless and forced beyond measure.
Whoever bears illness with patience and thanksgiving has it counted to him in place of spiritual effort, or even more than that.
An elder who suffered from dropsy said to the brothers who came to him wishing to treat him: “Fathers, pray that my inner man may not be afflicted with such a disease; but as for this present illness, I ask God not to free me from it all at once—for in proportion as ‘our outward man… perishes,’ in that same proportion ‘the inner man… is renewed’ (2 Cor. 4:16).”