This division into four parts applies only to Thessaly in the narrower sense, and is not so much of geographical interest, as it is of real political importance: there must at one time have existed four real Thessalian states standing to one another in the relation of isopolity, like the Romans and Hernicans, and the Samnite nations among one another. But this point, like all that concerns Thessaly, is involved in very great obscurity. This much, however, is certain, that the division was restored under Philip of Macedonia, who, for the purpose of breaking the power of Thessaly cut it up into four different states, just as afterwards the Romans did with Macedonia, and as, in 1812, Napoleon, while making the Poles believe that he was restoring their state, divided their country into three parts, in order to prevent its rising, at a great distance from him, to the rank of a powerful state. This is the tetrarchy of which Theopompus in Harpocration gives the well known explanation. Demosthenes (_Philip._ ii. p. 71, ed. Reiske), however, states that Philip divided Thessaly into decadarchies: this reading occurs indeed in all the MSS., but they are of little authority, as all of them are founded upon a single recension, and are perhaps derived from one original manuscript. From Harpocration, too, an author of the second century, we see that in his time this reading already existed, and puzzled him as well as other archaeologists. It is historically certain, that the Lacedaemonians, in every town that became subject to them, established a decadarchy, as at first they did at Athens, though they there increased the number to thirty; but how we have to view the statement in regard to Thessaly, is, as Harpocration admits, a matter of doubt. The explanation, however, is not so very difficult. The δεκαδαρχίαι in the second Philippic are, if we examine the context, quite the same as the tetrarchies in the third (p. 117). The fault arose from the compendious mode of writing: Δ in ancient Greek writing has, as a number, a double meaning; according to the common Phoenician practice it signified _four_, and according to the Attic system of writing _ten_. In nearly all the earlier inscriptions, where it occurs as a number, Δ signifies _ten_, as Π signifies _fifty_; when, therefore, Δ with a line (Δʹ) occurred before ἀρχία (ΔʹΑΡΧΙΑ), the reader knew that it indicated a number, but he made it either _ten_ or _four_, according as he imagined that he had before him an Attic or a common number; and if he was familiar with the Lacedaemonian decadarchy, he read in this passage also δεκαδαρχία. This division into tetrarchies, then, existed in the Macedonian period, but we do not know how long.