Ambrose on Baptism

What did you see? Water all around, but not alone; the levites [deacons] ministering there, the high priest [bishop] asking questions and sanctifying. First and foremost, the Apostle taught you that we should not contemplate what is visible, but what is not visible, since what is visible is temporal, but what is not visible is eternal.

Quid vidisti? Aquas utique, sed non solas: levitas illic ministrantes, summum sacerdotem interrogantem et consecrantem. Primo omnium docuit te Apostolus non ea contemplanda nobis quae videntur, sed quae non videntur, quoniam quae videntur, temporalia sunt: quae autem non videntur, aeterna [2 Cor 4.18].

—Ambrose, De mysteriis 3.8