Many who believe that heaven is a mere matter of admission from grace, and after admission there is eternal joy, were permitted to ascend into heaven; but because they could not endure the light and heat, that is, the faith and love there, they cast themselves down headlong; and they appeared to those who stood below like dead horses. Among those who stood below and who thus saw them, were boys with their master; and he taught them what their appearing like dead horses signified, and who those are who so appear at a distance, saying that they are those who when they read the Word think materially and not spiritually about God, the neighbor, and heaven; and that those think materially about God who think about essence from person, and in regard to the neighbor about his quality from the face and speech, and in regard to heaven about the state of love there from place; but those think spiritually who think of God from essence, and from essence of person; of the neighbor from his quality; and from quality of his face and speech; and of heaven from the state of love there and of place from that. And afterwards he taught them that a horse signifies understanding of the Word; and because the Word with those who think spiritually when they read it is a living letter, so such appear at a distance as living horses; and on the other hand, because the Word with those who think materially when they read it is a dead letter, so those at a distance appear as dead horses (From TCR 623).
Synopsis of a Memorable Relation ~ Emanuel Swedenborg
(True Christian Religion 852: LXII)