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.

56. Saying to me, "Do not be afraid." This symbolizes a revival, and from the deepest humility then, adoration.

That it means a revival or bringing back to life follows from what we said just before this in no. 55; and it is apparent that it includes an adoration from the deepest humility, since John fell at the Lord's feet. Moreover, because upon his revival a holy fear seized him, the Lord said, "Do not be afraid."

A holy fear is sometimes combined with a reverent trembling of the interior constituents that belong to the mind, and sometimes with a standing on end of the hair, and it comes over a person when life from the Lord enters in place of one's own life. One's own life is to look to the Lord from oneself, while life from the Lord is to look to the Lord from the Lord, and yet doing so as though of oneself. When a person is seized by this life, he sees that he is nothing, and that only the Lord is anything.

Daniel was seized by this holy fear when he saw a man clothed in linen garments, whose loins were girded with the gold of Uphaz, his body like beryl, his face like lightning, his eyes like torches of fire, and his arms and his feet like the sheen of burnished bronze. On seeing him Daniel, too, became as though dead, and a hand touched him, and a voice said, "Do not fear, Daniel" (Daniel 10:5-12).

Something similar happened with Peter, James and John when they saw the Lord transfigured and He appeared with a face like the sun and garments like light, on which account they also fell on their faces and feared for themselves greatly, and Jesus then came and touched them, saying, "Do not be afraid for yourselves" (Matthew 17:2, 6-7).

The Lord also said to women who saw Him at the sepulchre, "Do not be afraid" (Matthew 28:10) And an angel, whose countenance looked like lightning and his clothing like snow, said to the same women as well, "Do not be afraid for yourselves" (Matthew 28:3-5)

An angel also said to Zacharias, "Do not be afraid" (Luke 1:12-13).

The same holy fear seized Simon Peter because of the catch of fish, so that he said, "Depart from me, for I am a sinful man, O Lord!" But Jesus said to him, "Do not be afraid." (Luke 5:8-10)

And so on elsewhere.

We cite these instances to show why the Lord said to John, "Do not be afraid" - that it means a revival, and from the deepest humility then, adoration.