I am reading the LLPSI excerpt of Rhetorica ad Herennium (in LLPSI: Sermones Romani, Chapter Ostentator Pecuniosi). Near Line 64, Ørberg wrote a margin note:
pro notitia domini: quia domino notus erat
Notus erat is the passive pluperfect form of noscere, if the agent is mentioned, it is normally ablative and introduced by the preposition a/ab. However, here the (seeming) agent domino is used without a/ab.
What I can think of is, a bare ablative noun used for specification. If notus is regarded as an adjective, then domino can be in respect to the master. Ablative of cause seems also possible. But according to the context (below), he (the ostentator) enters another's house, and the dominus refers the house owner. He was known in respect to the house owner / because of the house owner are both weird in meaning.
What is the grammar here?
Context:
Dum haec loquitur, venit in aedes quasdam in quibus sodalicium erat eodem die futurum; quo iste – pro notitia domini aedium – ingreditur cum hospitibus.