Note 012
From Chapter 53 of the Decline & Fall

See Constantine de Thematibus, in Banduri, tom. i. p. 1 - 30. who owns that the word is is used by Maurice (Strata gem. l. ii. c. 2) for a legion, from whence the name was easily transferred to its post or province, (Ducange, Gloss. Graec. tom. i. p. 487-488.) Some etymologies are attempted for the Opiscian, Optimatian, Thracesian, themes.