That very existence which is God, neither Prophets, nor even Angels, nor yet Archangels, have seen. For enquire of the Angels; they say nothing concerning His Substance; but sing, Glory to God in the highest, and Peace on earth to men of good will. (Luke 2:1) Nay, ask even Cherubim and Seraphim; thou wilt hear only in reply the mystic melody of devotion, and that heaven and earth are full of His glory. (Is. 6:3)
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: Hom. xv. [xiv.] 1