In the opening fragment of Digest 18.1, Paul tells us that Sabinus and Cassius had not required a money price in sale. So long as you could distinguish buyer and seller, they had contended, the mere fact that the buyer paid with goods made no difference, but such a permutatio was sale. Sabinus had appealed to the authority of Homer, who says: ‘From there (i.e., from the ships sent by Euneus from Lemnos) the long-haired Achaeans procured wine, some for bronze, some for gleaming iron, some for hides, some for whole cattle and some for slaves’.

As these verses do not contain the term ‘sale’ at all, they are generally regarded as pointless; and it is held that all Sabinus can have meant to prove by them was that other things than money might be used for trading—a platitude for which he need not have-searched the ancient books. This, however, is doing him an injustice. As a matter of fact, he knew very well why he adduced just this passage. The word χαλκῷ here rendered as ‘for bronze’ was rendered as ‘aere’ by the Romans. Paul, in the very fragment under discussion, says that the Greeks obtained wine ‘aere ferrohominibusque’ One of the meanings of ‘aes’, as indeed of χαλκóς, was ‘money’. (One may think, for example, of ‘aes alienum’.) It was, therefore, possible to ascribe to χαλκῷ in the passage quoted the sense of ‘for money’, instead of ‘for bronze’. Sabinus translated: ‘They procured wine, some for money, some for gleaming iron,’ etc.