1. This proposition is attributed to the Chinese logician Hui Shih or one of his contemporaries of the fifth century BCE. For further information see Hu Shih, The Development of the Logical Method in Ancient China, (Shanghai, Oriental Book Co., 1928) p. 118.
2. Aristotle, Metaphysics, Bk IX, 1049b-1050a, Hippocrates G. Apostle trans., (Bloomington, Indiana University, 1966) pp. 54-5.
3. S. F. Butler, Life and Habit, (London, Jonathan Cape, 1924) p. 134.
4. Richard Dawkins, The Selfish Gene, (New York, Oxford University Press, 1976) p. 22.