'Pouring out the vials upon the earth, which contained the plagues,' in Revelation 16:1, signifies influx of the reformed into the church, or into people who study and receive the doctrine of justification by faith alone.

(Odkazy: Apocalypse Explained 16; Apocalypse Revealed 676)

685. 16: 16:5 And I heard the angel of the waters saying. This symbolizes the Word's Divine truth.

The angel of the waters symbolizes nothing else but the Word's Divine truth, because waters symbolize truths (no. 50). And an angel symbolizes the Divinity emanating from the Lord (nos. 415, 631, 633) and also the truth flowing from Him (no. 170).