I’m finding my study of Attic Greek also helping a lot to get back into Koine. Shortly after reading some discussions of diglossia in modern Greece, I was reading the Didache, and came across the following conclusive proof-text:
παγὶς Î³á½°Ï Î¸Î±Î½á½±Ï„Î¿Ï… ἡ διγλωσσία
There you have it. Diglossia is a deadly snare :-)
Update: even better:
τέκνον μου, μὴ γίνου … μαθηματικὸς … εκ Î³á½°Ï Ï„Î¿á½»Ï„Ï‰Î½ á¼Ï€á½±Î½Ï„ων εἰδωλολατÏία γεννᾶται
“My child, do not become … a mathematician … for from all that comes idolatry.” Could have used that advice before I went to university!