9515. 'Covering over the mercy-seat with their wings' means spiritual realities that provide cover. This is clear from the meaning of 'covering over the mercy-seat' as providing cover for the good through which lies access to the Lord; and from the meaning of 'wings' as the truths of faith or spiritual truths, dealt with immediately above in 9514, and in 8764. The spiritual realities are said to provide cover for the good because in heaven what is celestial, the good of love, manifests itself as something naked; but when it manifests itself through spiritual realities, which are the truths of faith, it is seen as something clothed.

Seven, as in Revelation 15:1, signifies everything in an universal sense. The number 'seven' was considered holy, as is well known, because of the six days of creation, and the seventh, which is the celestial self, where peace, rest, and the Sabbath is. The number seven occurs so frequently in the rites of the Jewish church and is held holy everywhere.

So times were divided into seven, longer and shorter intervals, and were called weeks, like the great intervals of times till the coming of the Messiah, in Daniel 9:24-25. The time of seven years is called 'a week' by Laban and Jacob, as in Genesis 29:27-28. So wherever the number seven occurs, it is considered holy and sacred, as in Psalm 119:164, and in Isaiah 30:26.

As the periods of a person's regeneration are distinguished into six, prior to the seventh, or the celestial self, so the times of vastation are also distinguished, until nothing celestial is left. This was represented by the many captivities of the Jews, and by the last Babylonian captivity, which lasted seven decades, or seventy years. This was also represented by Nebuchadnezzar, in Daniel 4:16, 22, 29. It also refers to the vastation of the end times, in Revelation 15:1, 7-8. They should 'tread the holy city under foot, forty and two months, or six times seven,' as in Revelation 11:2 and Revelation 5:1. So the severity and increments of punishment were expressed by the number seven, as in Leviticus 26:18, 21, 24, 28 and Psalm 79:12.

(Verweise: Apocalypse Explained 5, 7-8, 15; Arcana Coelestia 395; Daniel 9, 9:24, 9:25; Psalms 119)