I like medieval church songs, and recently I bought one CD, and
when I saw the rylic in the leaflet of the CD I found this use of de difficult.
unde de divina rationalitate,
que te speculum suum fecit coronata es.
I checked L&S, but there I couldn't find matching meaning other than
7. To indicate the thing in conformity with which any thing is done, according to, after
5. To indicate the producing cause or reason, for, on account of, because of
But here, this rationalitas looks as if it were an agent.
In L&S there is no entry of meaning for de as by denoting an agent.
In the medieval Latin, could de mean by(agent) ?