'Salt' symbolizes the desire of truth and good to be conjoined with each other. So, a salt can conjoin water, which corresponds to truth, with oil, which corresponds to good.

Salt can also have a negative meaning. 'Lot's wife becoming a statue of salt' signifies all the good of truth being vastated, or laid waste, in the church that Lot represented. In that story, Lot's wife represented a form of 'truth' that turned itself away from 'good,' and looked instead to doctrinal matters. Because 'salt' can signify vastation, and 'cities' signify doctrinal aspects of truth, in old times they sowed cities with salt when they were destroyed to prevent them from being rebuilt, as in Judges 9:45

(참조: Arcana Coelestia 10300)

4906. 'Bring her out, and let her be burnt' means that it - that is to say, the internal aspect of the Church which Tamar represented - should be exterminated. This is clear from the meaning of 'bringing her out, and burning her' as exterminating, 'bringing out' having reference to the truth and 'burning' to the good which were to be exterminated. The use of 'burning' in reference to the extermination of good is clear from many places in the Word. The reason for the usage is that in the spiritual sense 'fire' and 'flame' mean good, 934, and the heat radiated from them the affection for good, while 'fire' and 'flame' in the contrary sense mean evil, and the heat radiated from these the affection for evil, 1297, 1861, 2446. Also, in actual fact good is spiritual fire from which spiritual heat which is life-giving is radiated; and evil too is a fire, but from this a heat which is a consuming one is radiated. Anyone who turns his attention to this matter and reflects on it can plainly see that the good of love is spiritual fire, and that the affection for that good is spiritual heat if he reflects on the question where do man's vital fire and heat come from, he will discover that love is the source of it; for as soon as love departs a person begins to grow cold, but as love increases in him he becomes warmer. Unless man's vital fire and heat came from that source he could not possibly have life at all. But this life-bringing fire or spiritual heat becomes among the evil a destroying and consuming fire, for in their case it is converted into this kind of fire. Among living creatures which do not possess reason spiritual heat likewise flows in and brings life, but life which is varied, depending on the ways in which their organic forms, and therefore their knowledge and innate affections receive that life, as with bees and all other creatures.