Apocalypse Explained # 259
259. Verse 1. After these things I saw, and, behold, a door opened in heaven; and the first voice which I heard, as it were of a trumpet speaking with me, saying, Come up hither, and I will show thee things which must come to pass hereafter.
"After these things I saw," signifies the understanding enlightened; "and, behold, a door opened in heaven," signifies the arcana of heaven revealed; "and the first voice which I heard" signifies revelation now of things to come; "as it were of a trumpet speaking with me," signifies what is clear and manifest; "saying, Come up hither," signifies elevation of mind, and attention: "and I will show thee things which must come to pass hereafter," signifies instruction concerning those things that will exist in the last time of the church.
Spirit of God
'The spirit of God,' as in Genesis 1:2, signifies the divine mercy of the Lord.
'The spirit of God' denotes good from an interior level, so from the divine. The spirit of God is what proceeds from the divine, so from good itself, because the divine is good itself, and what proceeds from it is truth within which is good. This is what 'the spirit of God' signifies in the Word, because the spirit itself does not proceed, but the truth itself within which is good, the spirit being the instrument which produces it.
(Referências: Arcana Coelestia 19; Divine Love and Wisdom 100)