For many years it has been recognized that serious contradictions exist in Polybius’ theory of the Roman constitution, as he expounds it in Book VI. The position has been summarized in a review of a recent publication which attempts, not very successfully, to dispose of these inconsistencies. ‘The only point of controversy’, writes De Sanctis, ‘can be whether these contradictory elements were innate in Polybius’ political philosophy and in his judgement on Rome, or whether they repre-sent two successive stages in the historian's thought, and two successive drafts of the book itself, which either the author or the editor failed to co-ordinate.’ De Sanctis’ own view is, of course, the second; and indeed, ever since 1902, when Cuntz, following hints thrown out by La-Roche, Meyer, and Susemihl, first propounded the theory of a revised edition of Polybius’ Staatstheorie, it has exercised a dominating influence over all work on the subject.