Horse
In Ezekiel 26:11, this signifies the love of learning or intellectual things. (Arcana Coelestia 3727)
In Revelation 6:2, this signifies the love of understanding the Word. (Apocalypse Revealed 298)
In Zechariah 12:4, this signifies that the intellectual should be filled with falsities. (Arcana Coelestia 2383[2])
In general, 'a horse' signifies knowledge or understanding of the Word. In an opposite sense it signifies the understanding of the Word falsified by reasonings, and likewise destroyed from self-derived intelligence. 'A dead horse' signifies no understanding of truth from the Word.
Joel 2:4-9
4
The appearance of them is as the appearance of horses, and as horsemen, so do they run.
5
Like the noise of chariots on the tops of the mountains do they leap, like the noise of a flame of fire that devours the stubble, as a strong people set in battle array.
6
At their presence the peoples are in anguish. All faces have grown pale.
7
They run like mighty men. They climb the wall like warriors. They each march in his line, and they don't swerve off course.
8
Neither does one jostle another; they march everyone in his path, and they burst through the defenses, and don't break ranks.
9
They rush on the city. They run on the wall. They climb up into the houses. They enter in at the windows like thieves.
