The Return of the King (The Lord of the Rings, #3)

by J.R.R. Tolkien

His grief he will not forget; but it will not darken his heart, it will teach him wisdom.’

This was spoken by Aragorn about Merry after he was injured in the battle with the Witch-King. And isn't it true, though? Grief isn't easy to forget. But it does teach us wisdom.