Arcana Coelestia#7569
7569. 'And there will be hail in all the land of Egypt' means destructive falsity in the natural mind. This is clear from the meaning of 'hail' as destructive falsity arising from evils - destructive of all the goodness and truth of the Church, dealt with in 7553; and from the meaning of 'the land of Egypt' as the natural mind, dealt with in 5276, 5278, 5280, 5288, 5301.
Arcana Coelestia#6314
6314. As it is with light, so it is with the heat that is vital to a person's existence. In no way at all does that vital heat originate in the heat radiated by the sun in the world; rather, it originates in spiritual heat, which is love and radiates from the Lord. This heat is what angels have. Consequently the amount of vital heat a person has is determined by the amount of love he has. His body however is warmed by worldly heat, as is his sensory awareness within it; yet vital heat flows into that worldly heat and imparts life to it. Differences in the purity and intensity of this heat are akin to variations in the clarity of the light. This vital heat is what one should understand by the holy fires mentioned in the Word, and therefore heavenly loves are meant by those fires. But in a contrary sense that worldly heat is what one should understand by the fires of hell, and therefore hellish loves and the desires that go with them are meant when these fires are mentioned in the Word.