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.

782. And his mouth as the mouth of a lion, signifies reasonings from falsities destroying the truths of the church. This is evident from the signification of "mouth," as being thought (See above, n. 580), but here reasoning (of which presently); also from the signification of a "lion," as being infernal falsity in respect to its power (of which above, n. 278. This is because a "lion" signifies the Divine truth, for which reason the Lord also is called "a lion" in the Word; consequently in the contrary sense a "lion" signifies infernal falsity in respect to its power to destroy divine truth, and thus the Word; and this is especially done by adulterations and falsifications of it. And as a lion is the most powerful of animals, and its power increases according to its hunger to devour and consequently to seize its prey and tear it in pieces, so a "lion" signifies also the eagerness to destroy the truths of the Word. "Lions" have a like representation in the spiritual world, for lions also appear there, but the forms of lions are appearances arising from the eagerness of those who have great power to adulterate and falsify the truths of the Word whereby they are destroyed; with them this power increases according to their ability to reason. This is why "lions" signify in the Word in the contrary sense infernal falsity destroying the truths of the church. Because this is what a "lion" signifies, and because "the beast that was like unto a leopard" and that "had feet as of a bear" signifies the reasonings confirming the separation of faith from life, by which the goods and truths of the Word are adulterated and falsified; therefore the "mouth" of that beast, which was "as the mouth of a lion," signifies reasoning from falsities that destroy the truths of the Word. The "mouth," in a strict sense, signifies thought; but as man's speech is from the mouth, the "mouth" signifies the various things that flow from thought, as instruction, preaching, reasoning; here reasoning, because reasonings from the natural man are signified by the "beast" here treated of. But more will be said about this in the explanation of verses 5-7 of this chapter, in which are these words: "And there was given unto him a mouth speaking great things and blasphemies; and there was given unto him authority to make war forty-two months. And he opened his mouth in blasphemy against God, to blaspheme His name and His tabernacle and them that dwell in heaven. And it was given unto him to make war with the saints and to overcome them." From that explanation it will be seen what power and eagerness, and what ability such have to falsify the truths and adulterate the goods of the Word by means of reasonings.