If indeed transubstantiation occurs, and the bread and wine become the body and blood of Jesus Christ, why does John of Damascus1 (as an example) refer to the Eucharist as «ἀναίμακτον θυσίαν», "a bloodless sacrifice" (or "unbloody sacrifice")?
1 John of Damascus: On the Immaculate Body which We Partake Of (Περὶ τοῦ ἀχράντου σώματος, οὗ μεταλαμβάνομεν), Sec. I.
Compare the footnote on this page:
1988 unbloody Priesthood, ἀναίμακτον ἱερωσύνην, i.e. “sacerdotium,” not“sacrificium.” This, not θυσίαν, is supported by the Codd. The Eucharist is often called by the Fathers “the unbloody sacrifice” (e.g. Chrysost. in Ps. xcv., citing Malachi), and the Priesthood which offers it can be called “unbloody” too. Cf. Greg. Naz. in Poem. xi. 1—
῏Ω θυσίας πέμποντες ἀναιμάκτους ἱερῆες.
While these terms assert the sacrificial nature of the Eucharist, might they not at the same time supply an argument against the Roman view of Transubstantiation, which teaches that the actual blood of Christ is received, and makes it still a bloody sacrifice?