I ask all who find it hard to reconcile the prevalence of disease and pain with the love of God to observe the extent to which men constantly submit to present loss for the sake of future gain; present sorrow for the sake of future joy; present pain for the sake of future health. The seed is thrown into the ground, and rots: but we sow in the hope of a future harvest. The father of a family undergoes some fearful surgical operation: but he bears it, in the hope of future health. I ask men to apply this great principle to God's government of the world. I ask them to believe that God allows pain, sickness, and disease, not because He loves to vex man, but because He desires to benefit man's heart, and mind and conscience, and soul, to all eternity.
(a) Sickness helps to remind men of death. The majority live as if they were never going to die. They follow business, or pleasure, or politics, or science, as if earth was their eternal home. They plan and scheme for the future, like the rich fool in the parable, as if they had a long lease of life, and were not tenants at will. A heavy illness sometimes goes far to dispel these delusions. It awakens men from their day-dreams, and reminds them that they have to die as well as to live. Now this, I say emphatically, is a mighty good.
c) Sickness helps to soften men's hearts, and teach them wisdom. The natural heart is as hard as a stone. It can see no good in anything which is not of this life, and no happiness excepting in this world. A long illness sometimes goes far to correct these ideas. It exposes the emptiness and hollowness of what the world calls "good" things, and teaches us to hold them with a loose hand. The man of business finds that money alone is not everything the heart requires. The woman of the world finds that costly clothes, and novel-reading, and the reports of balls and operas, are miserable comforters in a sick room. Surely anything that obliges us to alter our weights and measures of earthly things is a real good
d)Sickness helps to level and humble us. We are all naturally proud and high-minded. Few, even of the poorest, are free from the infection. Few are to be found who do not look down on somebody else, and secretly flatter themselves that they are "not as other men." A sick-bed is a mighty tamer of such thoughts as these. If forces on us the mighty truth that we are all poor worms, that we "dwell in houses of clay," and are "crushed before the moth" (Job 4:19), and that kings and subject, masters and servants, rich and poor, are all dying creatures and will soon stand side by side at the bar of God. In the sight of the coffin and the grave it is not easy to be proud. Surely anything that teaches that lesson is good.
e)Finally, sickness helps to try men's religion, of what sort it is. There are not many on earth who have no religion at all. Yet few have a religion that will bear inspection. Most are content with traditions received from their fathers, and can render no reason for the hope that is in them. Now disease is sometimes most useful to a man in exposing the utter worthlessness of his soul's foundation. It often shows him that he has nothing solid under his feet, and nothing firm under his hand. It makes him find out that, although he may have had a form of religion, he has been all his life worshipping "an unknown god." Many a creed looks well on the smooth waters of health, which turns out utterly unsound and useless on the rough waves of the sick-bed. The storms of winter often bring out the defects in a man's dwelling, and sickness often exposes the gracelessness of a man's soul. Surely anything that makes us find out the real character of our faith is good.
Excerpts from J.C. Ryle on Sickness