Picked this up from Zygmunt Bauman's LSE lecture (he uses a lengthier quote) I just listened to on iTunes. I believe it comes from the book Philosophy and Social Hope.
We should raise our children to find it intolerable that we who sit behind desks and punch keyboards are paid ten times as much as people who get their hands dirty cleaning our toilets and a hundred times as much as those who fabricate our keyboards in the third world. We should ensure that they worry about the fact that the countries which industrialised first have a hundred times the wealth of those which have not yet industrialised. Our children need to learn early on to see the inequalities of between their own fortunes and those of the children as neither the will of God nor the necessary price of economic efficiency but as an evitable tragedy. They should start thinking as early as possible about how the world might be changed so as to ensure that no-one goes hungry while others have a surplus.