Constantine VII Porphyrogenitus about the etymology of the term "Theme"
Αὐτὸ γὰρ τὸ ὄνομα τοῦ θέματος ἑλληνικόν ἐστι καὶ οὐ ῥωμαικόν, ἀπὸ τῆς θέσεως ὀνομαζόμενον
A. Pertugi (edit.), Constantino Porfirogenito, De Thematibus, (Studi e testi 160, Città del Vaticano 1952), 1.27-28.