4803. A matter wholly unknown in the world and worthy of mention is this: The states in which good spirits and angels live undergo constant change and perfection. In this way they are conveyed to the more internal parts of the province in which they dwell, and so into more excellent functions. For in heaven purification takes place constantly, which is so to speak a new creation. Yet the situation is that no angel to all eternity can possibly attain complete perfection. The Lord alone is the perfect One, He being the root and the source of all perfection. Those who correspond to the mouth constantly wish to be speaking, for speaking gives them utmost pleasure. While undergoing perfection they are restricted to speaking nothing but that which is beneficial to companions, the community, heaven, and the Lord. The delight they take in speaking in that way grows in the measure that the desire to regard themselves in what they speak and to strive after wisdom from what is properly their own passes away from them.

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.