In Ezekiel 16:7, the breast signifies natural good.

(Referencat: Arcana Coelestia 3301)

In Exodus 29:26, this signifies the divine spiritual in the heavens and its appropriation there. It also signifies the good of charity. (Arcana Coelestia 10087)

Fire, in the spiritual sense, can mean either love or hatred depending on the context, just as natural fire can be either comforting in keeping you warm, or scary in burning down your house. Our language reflects this, too -- we use concepts like a smoldering hatred or a burning love. So fire signifies a love, either a good love of the neighbor and to the Lord, or, in a bad sense, selfish love of oneself that, if unchecked by conscience, leads to hatred of anyone that opposes it.