The word “open” can be used many different ways, and can be an adjective or a verb, so it’s hard to give one idea of its spiritual meaning that will cover all cases.
When used as a verb, though, it generally relates to gaining knowledge and understanding. This is easy to see in uses like opening the eyes, since seeing represents the intellect, or like opening a book. The meaning has to be looked at in context, though: Opening the mouth, for instance, takes much of its meaning from “mouth,” and could vary depending on whether the person is eating or speaking. Opening a door takes much of its meaning from what lies beyond the door, and who or what is passing through it, and why.
Passages from Swedenborg
Apocalypse Revealed (Coulson) n. 259
259. Who is worthy to open the book and to loose the seals thereof?’ signifies Who is in the power of getting to know the states of life of all in the heavens and on earth (in terris), and of judging each one in accordance with his own [state]? ‘Who is worthy?’ signifies who is able or who is in the power? ‘Toopen the book and to loose the seals thereof’ here signifies to get to know the states of life of all in the heavens and on earth, and also to judge each one in accordance with his own state, for when the book is opened there is an inquiry regarding their quality, and then the sentence or judgment, comparatively as a judge gives judgment (agit) with and out of a book of law. That by ‘to open the book’ is signified an inquiry regarding the quality of the states of life with all and with each one is plain from the following chapter, where what was seen when the Lamb opened the seven seals thereof in their order is described.
Apocalypse Explained (Tansley) n. 305
305. Verses 4, 5. And I wept much, that no one was found worthy to open and to read the book, neither to look therein. And one of the elders saith unto me, Weep not: behold, the Lion which is of the tribe of Judah, the Root of David, hath prevailed to open the book, and to loose the seven seals thereof.
“And I wept much, that no one was found worthy to open and to read the book, neither to look therein,” signifies, grief of heart on account of the disorder and ruin of all, if no one could know, have cognisance of, and explore all men, and all things pertaining to them.
Apocalypse Explained (Whitehead) n. 303
303. Who is worthy to open the book and to loose the seals thereof? signifies, is there anyone there such as to know and to perceive the states of life of all? This is evident from the signification of “Who is worthy?” as being, is there anyone who has merit and righteousness, and who has omniscience, thus whether there is any such? That “worthy,” in reference to the Lord, signifies merit and righteousness, which belong to Him alone, see above (n. 293). And that omniscience is signified is clear from what follows, where it is said, “the Lamb took the book out of the right hand of Him that sat upon the throne, and opened it;” for “right hand” signifies omniscience and omnipotence (see above, n. 297); it is evident also from the signification of the “book,” as being the states of life of all in general and in particular (of which see just above, n. 299); and also from the signification of “to open the book and to loose the seals thereof,” as being to know and perceive; for when the “book” signifies the states of life of all, “toopen and to loose the seals” signifies to know and perceive those states; for knowing and perceiving are predicated of the state of life, but opening and loosening seals relate to a book; thus the words in the internal sense conform to the things signified by the words in the sense of the letter, for they correspond; therefore, “to open” signifies to know, and “to loose the seals” signifies to perceive what is altogether hidden from others (as above, n. 300).
Arcana Coelestia (Elliott) n. 9266
9266. ‘For a gift blinds those whose eyes are open’ means that gain prevents truths from being seen. This is clear from the meaning of ‘a gift’ as any kind of gain, dealt with immediately above in 9265; from the meaning of ‘blinding’, when it refers to truths, as preventing them from being seen; and from the meaning of ‘those whose eyes are open’, or those who can see, as those who have a knowledge of truths and can see clearly what the truth is. For ‘seeing’ means knowing, understanding, and acknowledging truths, and also possessing faith, 897, 2150, 2325, 2807, 3764, 3863, 3869, 4403-4421, 5114, 5286, 5400, 6805, 8688, 9128. This explains why ‘those whose eyes are open’ are elsewhere called ‘the wise’,
A gift* blinds the eyes of the wise. Deut. 16:19.
* i.e. a bribe