That Aristotle criticizes Plato for separating the Forms is a fact known to every reader. However, what exactly it is that Aristotle wants to criticize has, until recently, seldom been discussed explicitly and at length, and indeed as exploration of the question has occurred, views have differed considerably. It has been proposed by some interpreters that when he criticizes Plato for separating the Forms, by ‘separation’ Aristotle means their independent existence, that is, their capacity for existing even if there were no sensible objects. But other interpreters have held that he means their numerical distinctness from sensible objects, and some writers have thought that he means both of these.

Thus despite the considerable importance Aristotle places on Plato's separation of the Forms, there is disagreement about just what he is objecting to.

At the beginning of Metaphysics VII 6 Aristotle inquires whether each thing and its essence are the same or different, an inquiry that, he claims, is of use for the investigation of substance. In Chapter III I will argue that VII 6 does indeed tell us much about substance. What is of relevance in this chapter, however, is Aristotle's preparedness to raise such a question. What Aristotle says of the inquiry into the sameness of each thing and its essence is that each thing is thought to be not different from its substance and that the essence is said to be the substance of each thing (1031a15–19). It is easy enough to suppose that ‘is not different from’ means ‘is the same as’ and that ‘is the same as’ means ‘is identical with’. If this assumption is made, there would not seem much need for inquiry: If each thing is identical with its substance and its substance is identical with its essence, then obviously each thing is identical with its essence.

Nevertheless Aristotle does inquire about the relation between each thing and its essence, a way of proceeding that suggests that the sort of sameness that interests him may in fact not be identity.

On the interpretation of Aristotle's account of substance I have just offered, substances are specimens of natural kinds that are numerically the same as sensible objects without being identical with them. Further, in virtue of their indistinguishability from one another (within the same kind), specimens of kinds have the knowability characteristic of the Forms without the separation; indeed it would not mischaracterize Aristotle's theory to say that it treats each specimen of the kind human being as if it were The Human Being – each specimen of a kind, in other words, as if it were the Platonic Form.

But even if specimens of natural kinds meet the requirement set forth in Metaphysics VII 1 that substances must be first in knowledge and definition, mere knowability on the part of substances does nothing to establish that they can be known by us. After all, one of the most serious difficulties with the Theory of Forms is that even though Forms are said to be eternal, unchanging, and the objects of definition, knowledge of them remains problematic. I contend that Aristotle believes his rejection of the separation of Forms can address this issue also – that is to say, he believes that his view enables him to explain how it is that there is knowledge.

The Statesman (or Politicus) is central to any serious concern with Plato's political thought. It clarifies and modifies Plato's earlier positions, especially in the Republic, and illuminates the principles of his political thinking even while these are in the process of changing.

Plato (429–347 bc) is known and discussed widely as a political thinker, but usually on the basis of his best-known work, the Republic, and this is in many ways a pity. The Republic is a work in which political theory is mixed together with ethical theory and metaphysics, and the political strand (which is not a very large one) is hard to disentangle and open to many different kinds of interpretation. Further, the political ideas, though expressed with vigour, are very sketchy, and their relation to contemporary political reality is remote. Plato's later works, Statesman and Laws, are more properly seen as works of political theory than is the Republic, and studying them can both help us to understand the Republic better, and also put it into perspective, as being only part of a long development in Plato's thinking.

In the Statesman, for example, Plato defends the ideal of the ruler as possessor of a particular kind of expertise, namely expertise in the ‘political skill (or art)’ (politikē technē). This idea dominates the political aspect of the Republic: political problems are to be solved by imposing an ideal ruler, and the only interesting question is what the nature of that rule is to be.

In preparing this translation, the Oxford Classical Text (E.A. Duke, W.F. Hicken, W.S.M. Nicoll, D.B. Duke and J.C.G. Strachan, eds., Platonis Opera, vol. I, Oxford University Press, 1994) has been followed, except in the few places indicated in the notes. We are extremely grateful to David Robinson for letting us see a copy of the text of Statesman in advance of publication.

The canonical essay on Plato's style of writing in his later dialogues remains the General Introduction by Lewis Campbell to his 1867 edition of Sophist and Statesman combined (see the bibliography on pp. xxviii–xxix). Here I need only point out to the reader that the Greek of Statesman is occasionally difficult and dense, and that it rarely rises to the conversational fluency and brilliance of Plato's early and middle-period dialogues. At the same time, he sometimes experiments – for no very good reason that I can see – with artificial alliteration, word order and rhythm. It is in the nature of translating from one language to another that these rhetorical devices are likely to be lost: they certainly have been in the following translation. Otherwise, my intention has been to keep as close to the Greek as a reasonable degree of fluency allows, without losing the occasionally dry and laborious tone of the original. Apart from this tone, however, there is little in the way the dialogue has been written to deter a potential reader, and (as always in Plato) enough thought-provoking material to make a reading worthwhile.

socrates: I'm really very grateful to you, Theodorus, for introducing me to Theaetetus. And thanks for the introduction to our visitor as well.

theodorus: You'll probably be three times as grateful, though, Socrates, when they've completed their portraits of the statesman and the philosopher as well.

socrates: All right – if this is what you want us to report as the view of our foremost arithmetician and geometer, Theodorus.

theodorus: What, Socrates?

socrates: That he counted each of the men as equivalent, when their relative values progress by leaps that are too great for you mathematicians with your ratios.

theodorus: That's a good point, Socrates. I call on Ammon, the god of my race, to witness that I admit it. You're quite right to tell me off for my mathematical mistake. Thanks for the reminder. I'll get my own back on you another time, but for now I'd like to ask our visitor to continue his kindness and next to pick either the statesman or the philosopher, whichever he likes, and give us an account of him.

visitor: Yes, I'd better, Theodorus. I mean, once we've undertaken a project, we oughtn't to give up until we've reached the end. But what should I do about Theaetetus here?

theodorus: What do you mean?

visitor: Shall we give him a break and instead get Socrates here to join us in our exertions? What do you suggest?

It is perhaps appropriate for the Statesman to be the first of Plato's works to come out in the Cambridge Texts in the History of Political Thought; it is certainly the most neglected of Plato's political works, and the one most in need of a fresh presentation. The new translation provides a more accessible version than any hitherto available in English, and the introduction attempts to locate the dialogue in Plato's political thought, taking advantage of the enormous improvements in our understanding of this that recent discussions have produced. Few of these directly concern the Statesman itself, and we hope that this new translation will help to bring the work more centrally into discussions of Plato's political thought, along with the more familiar Republic and Laws.

The translation and textual notes are by Robin Waterfield, and the introduction and other notes by Julia Annas. Each of us, however, has read and commented on the other's work, and the result is the product of a harmonious collaboration that has been interesting and profitable for both of us. We hope that its fruits will introduce others to this uneven, often puzzling but seminal dialogue.

By the standards of any contemporary western political culture, ancient societies, both Greek and Roman, were strikingly hierarchical. Only in the programmatic dreams of the most wild-eyed reformers could we expect to find an ideological commitment to general social equality. Of course, the notion that there should be equality of political rights among those fortunate enough to be classed as full citizens was somewhat commoner. But what we might call the ‘real world’ of social relations was based on dramatic differences in status, power, and wealth, which few if any could seriously imagine challenging.

From the fourth century BC onwards political and social thinkers were reflectively aware of the important role played in such a society by the doing of ‘good deeds’, services or gifts to other members of society for which some sort of return, even if only the expression of gratitude, was normally expected. Although the idea is in some form as old as Greek culture itself, it is fitting that we find clearly expressed in a pseudo-Aristotelian letter to Philip of Macedon the notion that such good deeds and the return for them served to ‘hold together’ (sunechein) society.

Polybius' History book VI contains the most complete text of Hellenistic Greek political theory that has survived from antiquity and the only extended example of applied political theory. Polybius, an Achaean statesman turned historian, developed a political theory not to justify a political position, advocate an ideal constitution, or speculate on the nature of law, justice, political authority, or the relation of man to the state, but for the practical purpose of explaining and predicting historical events.

Polybius explicitly tells us that the sixth book of his History was intended to serve two functions: (1) to explain Rome's rise to power, specifically, ‘how and by what type of constitution nearly the whole of the inhabited world, in less than 53 years, was overpowered and brought under one rule, that of the Romans’ (1.1.5; III.1.4, 2.6; VI.2.2–3; cf. VIII.2.3; XXXIX.8.7); and (2) to enable astute readers to make intelligent, informed political decisions in a world dominated by Rome (VI.2.8–10), and, in the particular case of political leaders, to govern in such a way as to upgrade and perfect the constitutions of their several states (III.118.10–12). Polybius' attention was therefore directed toward the nature, effectiveness, and destiny of the Roman constitution (VI.11–57).