In general, trees represent the deepest and most significant intellectual concepts: the ones that come to us most directly from the Lord. This varies depending on us and our states: the people of the Most Ancient Church, who were in a state of loving the Lord, understood truth automatically and internally through what the Writings call "perception"; people in lower states (including most of us) have to work a little harder to learn it from the Word and by willing to follow the Lord. In other parts of the Bible, especially in the prophets and New Testament parables, the meaning of "tree" is broader, meaning not just a person's intellectual concepts but the whole person.

'Trees,' as in Joel 1:10-12, signify knowledges.

312. So I looked, and behold, a black horse. This symbolizes an understanding of the Word among them extinguished as to truth, thus extinguished as regards their doctrine.

We showed above that a horse symbolizes an understanding of the Word. Blackness symbolizes a lack of truth, thus falsity, because blackness is the opposite of whiteness, and whiteness is predicated of truth (nos. 167, 231, 232). Whiteness is also the result of light, while blackness results from darkness, thus from the absence of light, and light means truth.

In the spiritual world, however, blackness has a double origin, one resulting from the absence of a flaming light, the light possessed by inhabitants of the Lord's celestial kingdom, and the other resulting from the absence of a bright white light, the light possessed by inhabitants of the Lord's spiritual kingdom. The first kind of blackness has the same symbolism as a thick darkness, the second the same as a gloomy darkness. The two kinds differ from each other. One is dreadful, the other not so dreadful. It is the same with the falsities that they symbolize. The spirits who appear in a terrible darkness are called devils. They also abhor truth as owls do the light of the sun. In contrast, the spirits who appear in a darkness that is not so dreadful are called satanic spirits. They do not abhor truth, though they are still averse to it, and therefore they may be likened to barn owls, but the first to eagle owls.

The fact that blackness in the Word is predicated of falsity can be seen from the following passages:

Her Nazirites were brighter than snow... Darkened more than blackness is their form. (Lamentations 4:7-8)

...on the prophets... the day shall grow black. (Micah 3:6)

On the day that you go down to hell..., I will make Lebanon dark over you... (Ezekiel 31:15)

...the sun became as black as sackcloth of goat's hair... (Revelation 6:12)

The sun, moon and stars are darkened in Jeremiah 4:27-28, Ezekiel 32:7, Joel 2:10; 3:15, and elsewhere.

It was the third living creature that displayed the black horse because it had a face like a human being, which symbolized the Divine truth of the Word in respect to its wisdom (no. 243). Consequently it was this living creature that displayed the fact that there was no longer any truth of wisdom in the people who were third in order.