57. 'The plant yielding seed' is every truth that looks towards a use. 'The tree in which there is fruit' is the good that accompanies faith. 'Fruit' is what the Lord gives to the celestial man, while 'seed', the source of the fruit, is what He gives to the spiritual man. This is why it is said that 'the tree producing seed will be for you for food'. That celestial food is called 'fruit from a tree' is clear from the next chapter where the subject is the celestial man. Here let just that be mentioned which the Lord spoke through Ezekiel,

Beside the river there is rising up upon its bank, on this side and on that, every tree for food. Its leaf will not fall nor its fruit fail. It is re-born monthly, for its waters flow out from the Sanctuary, and its fruit will be for food, and its leaf for medicine. Ezekiel 47:12.

'Waters from the Sanctuary' means the life and mercy of the Lord, who is the Sanctuary; 'fruit' means wisdom, which is food for them; 'leaf' is intelligence, which is given them for a use, which is called 'medicine'. Spiritual food however is called 'a plant', as stated through David,

[Jehovah is] my Shepherd, I shall not want; He makes me ¹ lie down in green pastures. ² Psalms 23:1-2.

Footnotes:

The sun in the Bible represents the Lord, with its heat representing His love and its light representing His wisdom. “Daytime,” then, represents a state in which we are turned toward the Lord, receiving His love and being enlightened by His truth. And “nighttime,” obviously, represents states in which we are turned away from the Lord, left cold and blind to the truth. The most common word used for it in the New Christian theology is “obscurity.” The darkness is not absolute, of course. The light of the moon represents the understanding we can have based on facts and our own intelligence. But while the moon reflects some of the sun's light, it offers almost no heat, so this kind of understanding is a cold one, without the warmth of love. And at its darkest and coldest, night represents a state of judgment. This happens when a person -- or a church -- becomes so mired in evil and falsity that there is no light or heat. The Lord can then step in, separate the good from the evil, consign the evil to hell and begin rebuilding based on the remnant that is still good. Drastic as that sounds, it is something that we all go through repeatedly in various aspects of our loves, so that we can be rid of what is evil and let the Lord rebuild us as angels.