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.

8991. 'And he shall serve him forever' means into eternity. This is clear from the meaning of 'serving' as obeying, for slaves are those who obey and masters those who give orders (the fact that those represented by 'slaves' are those who did what was good from obedience, not from charitable affection, is clear from things stated previously); and from the meaning of 'forever' as into eternity. In the sense of the letter 'forever' here means servitude with his master to the end of his life; but in the internal or spiritual sense it means into eternity, because it refers to the state after death. The expression 'into eternity' is used because those who do what is good from faithful obedience and not from charitable affection, who were represented by 'slaves', cannot ever be brought in the next life to a state of good, that is, so that their actions spring from good; for everyone's life remains with them after death. What a person is like when he dies, so he continues to be, in keeping with the common saying, Where the tree falls, there it lies. Not that he continues to be what he is like around the time of death but what the whole course of his life has made him like when he dies. Therefore those who have learned during life in the world to do what is good solely from obedience, not from charity, remain the same into eternity. They are perfected in obedience, it is true, but they do not attain any degree of charity.