The fragments of the Presocratics can be read in Jonathan Barnes’s Early Greek Philosophy (London, 1987) and in Richard McKirahan’s Philosophy Before Socrates (Indianapolis, 1994). The McKirahan collection contains commentary, and an excellent philosophical introduction is Jonathan Barnes’s The Presocratic Philosophers (London, 1979).
Plato’s dialogues can be best read in Plato: Complete Works, ed. J. Cooper and D. Hutchinson (Indianapolis, 1998). There are also good translations of single dialogues, with commentaries and introductions, published by Oxford (in the World’s Classics series), Penguin, and Hackett. A good introduction is The Cambridge Companion to Plato, ed. Richard Kraut (Cambridge, 1992).
The standard translation of Aristotle is the revised Oxford translation, to be found in The Complete Works of Aristotle, ed. Jonathan Barnes (Princeton, 1984). Aristotle: Selections, ed. T. Irwin and G. Fine (Indianapolis, 1995) is a good introductory selection. A good introduction is The Cambridge Companion to Aristotle, ed. Jonathan Barnes (Cambridge, 1995).
Stoics, Epicureans and Sceptics can be read in B. Inwood and L. Gerson, Hellenistic Philosophy (Indianapolis, 1997), and also in A. A. Long and D. Sedley, The Hellenistic Philosophers (Cambridge, 1987). There is unfortunately no good English collection of the fragments of the Cyrenaics. For Pyrrhonism see Sextus Empiricus: Outlines of Scepticism, trans. Julia Annas and Jonathan Barnes (Cambridge, 1994), and also The Modes of Scepticism (Cambridge, 1985) by the same authors. A good introduction is R. Sharples, Stoics, Epicureans, Sceptics (London, 1996). For Middle Platonism see John Dillon, The Middle Platonists (Ithaca, 1997), and for Neoplatonism see R. T. Wallis, Neoplatonism (London, 1972).
Ancient philosophy is so varied that there is no good detailed history of the entire tradition by a single author. A very brief introduction is T. Irwin, Classical Thought (Oxford, 1989). Also good is C. Gill, Greek Thought (Oxford, 1995). W. K. C. Guthrie’s six-volume History of Greek Philosophy (Cambridge, 1962–1981), ends at Aristotle and is uncritical, but is a good guide to sources. Histories of ancient philosophy have for some time taken the form of studies of particular philosophies or issues, rather than a single narrative of the whole tradition. Many can be found in the bibliographies of the works mentioned below.
A introductory reader, with texts arranged round issues rather than chronologically, is Julia Annas, Ancient Voices of Philosophy (Oxford, 2000). A more comprehensive reader for advanced students, also arranged topically, is Terence Irwin, Classical Philosophy (Oxford, 1999).
Chapters on philosophy at various periods can be found in the Oxford History of the Classical World (Oxford, 1986). Excellent reference works are the Oxford Classical Dictionary, 3rd edition (Oxford, 1996), and The Encyclopaedia of Classical Philosophy, ed. Don Zeyl (Westport, 1996).
The forthcoming multi-author Cambridge History of Hellenistic Philosophy and Cambridge History of Greek and Roman Political Thought are good guides to the areas they cover.
An extremely useful series is the Cambridge Companions to Ancient Thought, edited by Stephen Everson. These are Epistemology (1990), Psychology (1991), Language (1994) and Ethics (1998).