If you teach others how many insects exist in this world, or when you look at the spots on the sun, or when you write an opera or a novel - we do these things for different purposes. But to teach people goodness is done only for the purpose of self-sacrifice, service to others, and you cannot express this teaching without self-sacrifice. Christ gave his life on the cross for a great purpose, not in vain. And a sacrifice or suffering is never in vain, and it will triumph over everything.