260. (Verse 1) After these things I saw. That this signifies the understanding enlightened is evident from the signification of seeing, as being to understand. The reason of this is that the sight of the eye corresponds to the sight of the mind, which is the understanding. This correspondence is based on the fact that the understanding perceives spiritual things, and the sight of the eye natural things; spiritual things are truths from good and natural things are objects in various forms. Truths from good, which are spiritual things, are seen in heaven as clearly as objects before the eye, but still with much difference, for those truths are seen intellectually, that is, are perceived. The nature of this sight, or perception, cannot be described in human language; it can be comprehended only by this, that it includes consent and confirmation from an inmost principle that the thing is so. For there are confirmatory reasons in very great abundance, which present themselves as one to the intellectual sight, and this one is as a conclusion from many. These confirmatory reasons are in the light of heaven, which is Divine truth, or Divine wisdom, proceeding from the Lord, and which operates in each angel according to the state of his reception; this is spiritual sight, or understanding.

[2] Because this sight operates into the sight of the eyes with the angels, and presents the truths of the understanding in correspondent forms, which in heaven appear not unlike the forms in the natural world which are called objects, therefore by seeing, in the literal sense of the Word, is signified to understand. (What the nature of appearances in heaven is, and that they correspond to the objects of the interior sight of the angels, may be seen in the work, Heaven and Hell 170-176.) The reason why in the Word it is not said to understand, but to see, is that the Word in its ultimates is natural, and what is natural is the basis on which spiritual things are founded; therefore, if the Word in the letter were also spiritual it would have no basis, thus it would be as a house without a foundation (concerning this subject also, see in the work, Heaven and Hell 303-310). That in the Word to see signifies to understand is evident from the following passages. In Isaiah:

"Who have said to the seers, See not, and to those who have vision, See not for us right things; speak to us blandishments, see illusions" (30:10).

Again:

"And the eyes of them that see shall not blink, and the ears of them that hear shall hearken" (32:3).

Again:

Ye blind, look in seeing, in seeing . . . great things, ye do not keep them" (42:18, 20).

Again:

"The priest and the prophet err through strong drink they err among the seeing, they stumble in judgment" (28:7), and elsewhere;

"Seeing they see not, and hearing they hear not" (Matthew 13:13-15; Mark 4:12; 8:17, 18; Isaiah 6:10; Ezekiel 12:2).

Besides many other passages, which need not be adduced here since everyone knows, from the customary modes of expression, that to see signifies to understand; hence we say, I see this, that it is, or is not so, meaning I understand.

[260 ½] And, behold, a door opened in heaven. That this signifies the arcana of heaven revealed, is evident from the signification of a door, as being introduction, concerning which see above (n. 208); in this case, looking into which is a letting-in of the sight; and the sight is let into heaven when the sight of the bodily eyes is made dim, and then the sight of the eyes of the spirit is enlightened; by the latter sight all the visions of the prophets were seen. The reason why a door opened in heaven here signifies the arcana of heaven revealed is that those things then appear which are in the heavens, and, before the prophets, those which are arcana of the church. In the present case were seen the arcana concerning those things that were to exist about the time of the Last Judgment, none of which have been as yet revealed, nor could they be revealed before the Judgment was accomplished, and not even then except by means of some one in the world to whom it should be granted by the Lord to see them, and to whom, at the same time, should be revealed the spiritual sense of the Word. For all the things written in this prophetical book are written concerning the Last Judgment, but by means of representatives and correspondences; for whatever is said by the Lord and perceived by the angels is turned into representatives when it descends, and is thus presented both before the eyes of the angels in the ultimate heavens, and before men who were prophets, when the eyes of their spirit were opened. From these considerations it is evident what is meant by a door opened in heaven.