'A horse' signifies knowledges or understanding of the Word. In an opposite sense it signifies the understanding of the Word falsified by reasonings, and likewise destroyed, as also self-derived intelligence.
(Odkazy: Apocalypse Revealed 298)
'A dead horse' signifies no understanding of truth from the Word.
(Odkazy: Apocalypse Revealed 225)
483. And he said to me, "You must prophesy again about peoples, nations, tongues, and many kings." (10:11) This symbolically means that such being the case, the character of people caught up in faith alone must be further told.
That this is the symbolic meaning is apparent from what follows, in which the subject is people caught up in faith alone, to the end of chapter 16. After that the subject is the Roman Catholic religion, then the casting out of the dragon, the beast, and the false prophet into hell, and afterward the New Church, which will worship the Lord alone.
To prophesy means, symbolically, to teach (nos. 8, 133), and so to prophesy again means to teach further. "Peoples" symbolize people who are impelled by doctrinal truths or doctrinal falsities, and "nations" symbolize people who are impelled by good practices or evil practices. More about these later. "Tongues" symbolize people who are impelled by truths and goods or falsities and evils externally (no. 282), and "kings" people who are impelled by them internally. To be shown that kings symbolize people who are impelled by truths springing from goodness, and in an opposite sense, people who are impelled by falsities springing from evil, and abstractly truths themselves springing from goodness or falsities themselves springing from evil, see nos. 20, 664, 704, 720, 830, 921. And as the subject in what follows is in particular people impelled by interior falsities, the text says, "and many kings," which symbolizes falsities accompanying evil in abundance.
The text says peoples, nations, tongues and kings in order to mean all people in the church who are of this character.
John's being told that he had to prophesy again means, symbolically, to teach further the character of people caught up in faith alone, in order that their falsities may be exposed and thus eradicated, since no falsity is eradicated before it has been exposed.
(Odkazy: Isaiah 18:2)
 That "peoples" symbolize people impelled by doctrinal truths or falsities, and "nations" people impelled by good or evil practices, can be seen from many passages in the Word where peoples and nations are mentioned. However, to demonstrate this we will cite here only some passages where peoples and nations are mentioned together, from which this conclusion may be drawn, as each and every particular in the Word contains a marriage of the Lord and the church, and consequently a marriage of goodness and truth; and "peoples" refer to truth, and "nations" to goodness. The presence of such a marriage in each and every particular of the Word may be seen in The Doctrine of the New Jerusalem Regarding the Sacred Scripture, nos.80-90.
 Here are the passages in the Word:
Woe to a sinful nation, to a people laden with iniquity... (Isaiah 1:4)
I will send him against a hypocritical nation, against the people of My wrath I will command him... (Isaiah 10:6)
(Jehovah) who is striking the peoples... with an incurable plague, who is ruling the nations in anger... (Isaiah 14:6)
At that time a present will be brought to Jehovah..., a people scattered and shaven..., and a nation marked off and downtrodden... (Isaiah 18:7)
...a strong people will honor You, a city of mighty nations will fear You. (Isaiah 25:3)
(Jehovah) will swallow up... the covering... over all peoples, and the veil... over all nations. (Isaiah 25:7)
Come near, you nations..., and pay heed, you peoples! (Isaiah 34:1)
I... have called You... as a covenant to the peoples, and as a light to the nations. (Isaiah 42:6)
Let all the nations be gathered together, and let the peoples assemble. (Isaiah 43:9)
Behold, I will lift My hand... to the nations, and... My standard to the peoples. (Isaiah 49:22)
...I have given him as a witness to the peoples, a leader and lawgiver to the nations. (Isaiah 55:4)
Behold, a people is coming from the north country, and a great nation... from the edges of the earth. (Jeremiah 6:22)
Many peoples and numerous nations shall come to seek Jehovah of hosts in Jerusalem... (Zechariah 8:22)
Jehovah renders the counsel of the nations of no effect, He overturns the deliberations of the peoples. (Psalms 33:10)
(Jehovah) will subdue the peoples under us, and the nations under our feet... (Jehovah) reigned over the nations... The willing of the peoples have gathered together... (Psalms 47:3, 8-9)
The peoples shall confess You... The nations shall be glad... For You shall judge the peoples righteously, and guide the nations on the earth. (Psalms 67:3-4)
Remember me, O Jehovah, with good pleasure toward Your people..., that I may rejoice in the joy of Your nations... (Psalms 106:4-5)
...all peoples, nations, and languages shall worship (the Son of Man). (Daniel 7:14)
And so on elsewhere, as in Psalms 18:43, Isaiah 9:2-3; 11:10, Ezekiel 36:15, Joel 2:17, Zephaniah 2:9, Revelation 5:9, Luke 2:30-32.