George MacDonald, in his novel What's Mine's Mine:
There are tenderhearted people who virtually object to the whole scheme of creation. They would neither have force used nor pain suffered; they talk as if kindness could do everything, even where it is not felt. Millions of human beings but for suffering would never develop an atom of affection. The man who would spare due suffering is not wise. Because a thing is unpleasant, it is folly to conclude it ought not to be. There are powers to be born, creations to be perfected, sinners to be redeemed, through the ministry of pain, to be born, perfected, redeemed, in no other way.