Once I, Chuang Tzu, dreamed I was a butterfly and was happy as a butterfly. I was conscious that I was quite pleased with myself, but I did not know that I was Tzu. Suddenly I awoke, and there was I, visibly Tzu. I do not know whether it was Tzu dreaming that he was a butterfly or the butterfly dreaming that he was Tzu. Between Tzu and the butterfly there must be some distinction. This is called the transformation of things.