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.

'The former heavens, which passed away,' as mentioned in Revelation 21:1, signify the societies of people in the spiritual world who were only in external or apparent good. (Apocalypse Explained 675) Heavens are celestial and spiritual things. Consequently, they are inmost things, both of the Lord's kingdom in heaven and in the earth. This also refers to the church, and every individual, who is a kingdom of the Lord, or a 'church.' Consequently, heavens denote all things pertaining to love and charity, and faith grounded in them, as well as all things pertaining to internal worship. In like manner they denote all things pertaining to the internal sense of the Word. All these things are heavens, and are called, 'the throne of the Lord.' (Arcana Coelestia 2162)

(Odkazy: Apocalypse Explained 21)