'Vapor,' as in Jeremiah 10:13, signifies the ultimate truths of the church.

In Psalm 135:7, this signifies the ultimate, or most external truths of the church. (Apocalypse Explained 304[50])

In Psalm 148:8, this signifies the delights of the loves of the natural man and its external and internal knowledges. This is before a man has been reformed and made spiritual. (Apocalypse Explained 419[15])

(References: Apocalypse Explained 304)