It was unintelligible to me.

From Shakespeare’s Julius Caesar, 1601:

CASSIUS Did Cicero say any thing?
CASCA Ay, he spoke Greek.
CASSIUS To what effect?
CASCA Nay, an I tell you that, Ill ne’er look you i’ the
face again: but those that understood him smiled at
one another and shook their heads; but, for mine own
part, it was Greek to me.