John 9:

Bodily afflictions are all wisely ordered by the Lord, In every case they have an object. But they are not always sent in judgment, though men are prone so to interpret them when others are the subject of them. The disciples, when they saw a man blind from his birth, rashly concluded that it was a judgment either on his own sins or the sins of his parents. Jesus explained that it was not for any particular sin that he was born blind, but "that the works of God should be made manifest in him."He was born blind that Jesus might have an opportunity of giving him sight. All this previous affliction must be endured by the man that, at a particular time, God might be glorified by his cure.

And is not this great consolation to any of the Lord's people who may be subject to this or any similar affliction? They must not, indeed, expect to be relieved by a miracle; but they may rest assured that God has some purpose to serve by their affliction, and that in it they may glorify God more than they could otherwise have done. There are many ways in which this may be true; and each individual may discern something in his own case in which he can realize this. Christians are sometimes tempted to question God's love when they are greatly afflicted. Nothing can be more groundless. What is for God's glory in them, must be for a blessing to them; and in the school of Christ, discipline is as necessary as teaching.