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.

2194. 'And behold, Sarah your wife will have a son' means the Rational that was to be Divine. This is clear from the meaning of 'a son', also of 'Sarah', and of 'Isaac' as well, who was to be born to her. Both 'a son' and 'Sarah', and 'Isaac' too, mean that which is a feature of the Lord's Rational; for '5011' means truth, see 489, 491, 533, 1147, 'Sarah' rational truth, 2173, and 'Isaac' the Divine Rational, 1893, 2066, 2083. With everyone the human has its beginnings in the inmost part of the rational, as stated in 2106, so that the Lord's Human too had its beginnings there. That which was above it was Jehovah Himself, which is not the case with anyone else at all. Since the human has its beginnings in the inmost part of the rational, and since the Lord made the whole of the human with Him Divine, He first made the rational itself Divine from the inmost. And that rational, having been made Divine, is represented and meant, as has been stated, by 'Isaac'.