Êxodo 30
Bede
Êxodo 30:6
The ark of the covenant, which was inside the veil, … very suitably symbolizes the nature of [Christ's] humanity. The urn [containing] manna symbolizes the fullness of his divinity. The staff of Aaron symbolizes the indestructible power of his priesthood, [and] the tablets of the covenant symbolize that it is he who gave the law and will also give his blessing to those who fulfill the law. — Homilies on the Gospels 2.25
Êxodo 30:18
In the first instance, we can understand this basin (or flanged bowl, as it is called further on) to be the water of baptism, in which all those who enter the doors of the church must bathe in order to be cleansed. It was put between the tabernacle of the testimony and the altar of the holocaust, and the priests were commanded to wash themselves in it twice a day (that is, morning and evening) when they were going to the altar of incense to offer to the Lord. We, however, are not supposed to be washed in the water of baptism more than once; consequently the basin commends to us that washing of compunction and of tears which is required of us at all times, and especially when we draw near to minister at the heavenly mysteries. — On the Tabernacle 3.14, AT EXODUS 3:18-20
Êxodo 30:34
"You shall not offer upon it incense of another composition." Later in this book the spices from which this incense was to be composed are specified by name: stacte, and onycha, galbanum of pleasing fragrance, and the purest frankincense. It is obvious that all of these signify the eternal goods which we ought to seek from the Lord before anything else. Consequently upon the altar of gold they were not supposed to offer incense of any composition other than that which the Lord had decreed, because when we pray we ought to seek from the Lord nothing other than that which he himself has commanded and has promised to give us. And we ought to believe nothing concerning him other than that which he himself has taught. — On the Tabernacle 3.12, AT EXODUS 30:9