A-UN breathing-UN

The "A" in "A-UN" is to open your mouth and breathe out, and the "un" is to close your mouth and breathe in. "A-UN" is to breathe in and out. Beginning with "a" (阿) with the mouth wide open and ending with "un" (吽) with the mouth completely closed, "A-UN" is said to represent the universe from its beginning to its end.

In Japan, the mouths of the komainu (guardian dogs) and nio (guardians of the gods) at the gates of temples and shrines represent the "A-UN breathing" with one side opening its mouth and the other closing it.