Once I was travelling in England and someone invited me to see a school where concentration was taught. They brought before me ten or fifteen children, and each child was asked to look at a blank curtain, and say what was there. One child looked and looked and said, "A lily." Another child said, "A rose." The teacher asked a third child to tell her what was there. The child answered, "I don't see anything!" I thought, "That is much better; at any rate he says what he sees!" And so the teacher asked ten or twelve children questions about what they saw.