"What are we going to do?" I asked.
    "We will do what is required of us."
    "How will we know what that is?"
    "All is given in its season. All that is needful is granted. We have but to ask, and if our hearts are in the asking it will be granted."
    "Always"
    "You are full of questions, boy," the Wise Emrys chuckled. "No, not always. We serve at the Gifting God's pleasure. I him we move and have our being; in him we live both here and in the world to come. If anything is withheld from us, it is for the reason of a greater good to come."
    "Always?"
    This time the Emrys became adamant. "Oh, aye! Always. Goodness is ever good, and the All-Wise God is a good God. From him goodness itself derives its meaning."
    "So, even if evil overtakes us, it is still for the greater good," I said, trying to understand this philosophy.
    The Emrys accepted my foolish answer, but corrected it gently. "That is one way to say it, but perhaps not the best way. To see evil and call it good mocks God. Worse, it makes goodness meaningless. A word without meaning is an abomination. for when the word pases beyond understanding, the very thing the word stands for passes out of the world and cannot be recalled. 
    "This is a great and subtle truth, Aneririn. Think on it."
    I did, but could make no headway. "But," I said, returning to the former discussion, "if the Holy God is good and yet evil overtakes me, what am I to say?"
    "Only say, 'Evil has overtaken me.' God did not wish it, but being God he can use even that which is evil and meant for evil and turn it to good end. It is his labor in the world, and ours, to raise up the fallen and to turn the evil into good."
    This surprised me. "Because your sight was restored?"
    "No," he replied, "because it was not."
    Now I was confused. The Emrys saw me struggling with this and said, "It is because you do not believe that you do not understand."
    "But I want to understand."
    "The hear me: God is good; his gifts are granted each in its own season, and according to his purpose. I endured blindness that  I might discern the subtle ways of Darkness, and treasure the Light the more. When I learned this truth, it pleased God to restore my sight-which he did in time."

from Arthur (Book Three of the Pendragon Cycle)  by: Stephen R. Lawhead