1.Aristotle， Metaphysics， Book I， Chapter 3， 983b 6， 20 （Oxfordtrans.）。 Here and below I follow the standard practice of citing pas-sages from Aristotle by referring to their location in I. Bekker’s1831 Greek edition. By “Oxford trans.，” I mean that the Englishlanguage version is taken from The complete Works of Aristotle—The Revised Oxford Translation， ed. J. Barnes （Princeton Univer-sity Press， Princeton， N.J.， 1984）， which uses this convention inciting passages from Aristotle.
2.Diogenes Laertius， Lives of the Eminent Philosophers， Book I，trans. R. D. Hicks （Loeb Classical Library， Harvard UniversityPress， Cambridge， Mass.， 1972）， p. 27.
3.From J. Barnes， The Presocratic Philosophers， rev. ed. （Routledgeand Kegan Paul， London， 1982）， p. 29. The quotations in thiswork， hereafter cited as Presocratic Philosophers， are translationsinto English of the fragmentary quotations in the standard source-book by Hermann Diels and Walter Kranz， Die Fragmente derVorsokratiker （10th ed.， Berlin， 1952）。
4.Presocratic Philosophers， p. 53.
5.From J. Barnes， Early Greek Philosophy （Penguin， London， 1987），p. 97. Hereafter cited as Early Greek Philosophy. As in PresocraticPhilosophers， these quotations are taken from Diels and Kranz，10th ed.
6.From K. Freeman， The Ancilla to the Pre-Socratic Philosophers（Harvard University Press， Cambridge， Mass.， 1966）， p. 26. Here- after cited as Ancilla. This is a translation into English of the quotations7. Ancilla， p. 59.
8. Early Greek Philosophy， p. 166.
9. Ibid.， p. 243.
10. Ancilla， p. 93.
11. Aristotle， Physics， Book VI， Chapter 9， 239b 5 （Oxford trans.）。
12. Plato， Phaedo， 97C–98C. Here and below I follow the standard practice of citing passages from Plato’s works by giving page numbers in the 1578 Stephanos Greek edition.
13. Plato， Timaeus， 54 A–B， from Desmond Lee， trans.， Timaeus and Critias （Penguin Books， London， 1965）。
14. For instance， in the Oxford translation of Aristotle’s Physics， Book IV， Chapter 6， 213b 1–2.
15. Ancilla， p. 24.
16. Early Greek Philosophy， p. 253.
17. I have written about this point at greater length in the chapter “Beautiful Theories” in Dreams of a Final Theory （Pantheon， New York， 1992; reprinted with a new afterword， Vintage， New York， 1994）。
