Lernen
10 As for the likeness of their faces, they had the face of a man; and the four of them had the face of a lion on the right side; and the four of them had the face of an ox on the left side; the four of them also had the face of an eagle.
'To open,' as in Revelation 9, signifies communication and conjunction.
(Verweise: Apocalypse Explained 537)