Laudator Temporis Acti

Revelation 6:6 (tr. Richmond Lattimore):

And I heard as it were a voice in the midst of the four animals, saying: A measure of grain for a denarius, and three measures of barley for a denarius...

καὶ ἤκουσα ὡς φωνὴν ἐν μέσῳ τῶν τεσσάρων ζῴων λέγουσαν, Χοῖνιξ σίτου δηναρίου, καὶ τρεῖς χοίνικες κριθῶν δηναρίου...

David E. Aune, Revelation 6–16 (1998; rpt. Grand Rapids: Zondervan, 2014 = Word Biblical Commentary, Vol. 52B), p. 397:

χοῖνιξ σίτου δηναρίου, καὶ τρεῖς χοίνικες κριθῶν δηναρίου, "A liter of wheat for a denarius, and three liters of barley for a denarius." This statement suggests an exorbitant price for basic commodities during a period of famine caused either by drought or by war (about eight times the normal price for wheat and five-and-one-third times the normal price for barley) and indicates the relative value of wheat and barley. According to b. Sotạ 49b, produce will soar in price with the advent of the Messiah. One liter of wheat and three liters of barley are mentioned together here because it is the appropriate ration for a cavalryman and his mount, or for an individual and his domestic animals. Here the term "liter" is used as an equivalent to the Greek dry measure called a χοῖνιξ (choinix, pl. choinikes), roughly equal to a day's ration of wheat for one person (Herodotus 7.187; Xenophon Anabasis 7.3.23; Athenaeus Deipn. 3.98e; Diogenes Laertius 8.18; Livy 4.15.6). Three choinikes of barley was the approximate amount of daily fodder necessary to feed a horse (Polybius 6.39.13; see Stolle, Der römische Legionar, 59), while the ration of wheat for a Roman soldier was thirty-two choinikes per month (Polybius 6.39.13–15; two-thirds of a medimnos, which was forty-eight choinikes). 8 χοίνικες = 1 ἑκτεύς; 6 ἑκτεῖς = 1 μέδιμνος, i.e., a χοῖνιξ is 1/48 of a μέδιμνος. A choinix of barley or a half choinix of wheat per day was regarded as the normal ration for a slave (Thucydides 4.16.1; Athenaeus Deipn. 6.272c).

[....]

According to the Romans, a shortage in the grain supply could be considered a prodigium, i.e., a divinely sent sign foreshadowing coming disasters (Tacitus Annals 12.43; see Excursus 6A: Ancient Prodigies and the Plagues of Revelation).

The author's emphasis on a denarius as the cost of a liter of wheat and three liters of barley presupposes that this amount represents a daily wage for an average worker (Matt 20:1–16; Tob 5:14). The normal cost for a choinix of wheat was about one-eighth of a Greek denarius or two Roman asses, while barley was about half the cost of wheat, i.e., one-sixteenth of a Greek denarius or one Roman as (2 Kgs 7:1, 16; Polybius 2.15.1; Cicero Verrine Orations 3.81.188). During times of famine, grain prices could rise steeply. The prices mentioned in Xenophon Anabasis 1.5.5–6, for example, are fifty times the normal rates.