'A raven,' as in Genesis 8:7, signifies falsities. The spiritual self only knows general truths from the Word, and forms its conscience from these, and the general truths of the Word are accommodated to the fallacies of the senses. So countless falsities attach themselves, and insinuate themselves into those general truths, and they cannot be drawn out. These falsities are what 'the raven which went forth in going and returning' signifies. 'Sons of the raven,' as in Psalm 147:8, 9, signify natural people in a dim light arising from fallacies relating to divine truth.

(Odkazy: Arcana Coelestia 865)

In most cases, "mouth" in the Bible represents thought and logic, especially the kind of active, concrete thought that is connected with speech. The reason for this is pretty obvious, but it also holds when people, for instance, remove a stone from the mouth of a well, which represents gaining access to spiritual ideas. The mouth is used for eating as well as speaking, of course. In those circumstances, it represents our first, most external perception of a new spiritual idea or desire. This also makes sense, mirroring the way tasting food in the mouth gives us an instant impression of the quality of the food.