Glossa Ordinaria

I saw. Not only the living creatures and the ancients bearing witness to the same thing out of their office, but I also heard, The voice of angels. That is, of the supernal spirits who fortify and guard the Church, who rejoice over the restored fellowship of the saints, who bear testimony to Christ, both at his nativity, when they appeared to the shepherds, and at his passion, and at his resurrection and ascension they testified that the judge would come. Or the angels are the lesser subjects in the Church, leading an angelic life, who surround and honour their preachers and their judges, consenting to their testimony and conforming themselves to it. Of many round about the throne and the living creatures and the ancients, etc. The more they are, the greater the attestation and the greater the joy. Thousands of thousands. He set down this number, because that is finite with God which to men is infinite.