Right at the start of Book II we are faced with the statement that the Thebans attacked Plataea ‘when the archonship of Pythodorus at Athens had two months still to run, in the sixth month after the battle at Potidea, and at the beginning of spring’. ‘Two months’ cannot be reconciled with ‘at the beginning of spring’, given the facts of the Athenian civil calendar, and ‘the sixth month’, though defensible, is not very easy to reconcile with the narrative of Book I. Many times in reading Thucydides, if we care whether what he says is true, or even coherent, we have to question, and sometimes reject, the text. Numerical words give the most trouble, for an obvious reason: ‘sixth’, ‘ninth’, ‘tenth’, etc. are all equally grammatical and may all make equally good sense until investigated more deeply than we can expect of a copyist; Polybius (xii. 4a) knew that. There are, however, difficulties of other kinds. Did Thucydides say of Gylippus in vi. 104. I ‘after negotiating with Thurii and renewing the citizenship given to his father’ or (a variant reading) ‘after negotiating with Thurii in accordance with the citizenship once given to his father’? It makes some difference to our notions about Greek grants of citizenship. And in vi. 88. 4 leaving of πολλοί or emending to ού πολλοί makes a difference to our picture of the balance of power between Syracuse and Athens.