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.

1059. 'This is the sign of the covenant that I am establishing between Me and all flesh that is on the earth' means that it was a token of the Lord's presence in charity not only with the member of the Church but also with him who is outside the Church. This is clear from the meaning of 'all flesh' as all people, and therefore the whole human race. That the whole human race is meant, both those inside the Church and those outside the Church, is clear not only from the fact that the expression 'all flesh' is used but also that the expression 'living soul in all flesh', which appeared previously, is not used. And the point is made plainer still by the addition of the phrase 'which is on the earth'.

[2]That the Lord is as much present in charity with those outside the Church who are called gentiles as with those inside the Church may be seen above in 932, 1032. Indeed He is more present with them, for the reason that there is less cloud in the understanding part of their minds than is normally the case with so-called Christians. Indeed gentiles have no knowledge of the Word and do not know what the Lord is, and as a consequence do not know what the truth of faith is. This being so, they are incapable of opposition to the Lord and to the truth of faith. Consequently their cloud does not stand in opposition to the Lord or to the truth of faith, such cloud being dispersed easily when they are enlightened.

[3] But the cloud existing with Christians does stand in opposition to the Lord and to the truths of faith, and this cloud is so obscure as to be darkness. And when hatred is there instead of charity it is thick darkness. This applies even more to people who profane the truths of faith, something gentiles are incapable of doing because they live in ignorance of the truth of faith. Nobody can profane that of which he does not know the nature or the existence. This explains why more of the gentiles are saved than of Christians, as also the Lord said, in Luke 13:23, 28-30, in addition to saying that their children all belong to the Lord's kingdom, Matthew 18:10, 14; 19:14; Luke 18:16.