3893. Angelic choirs were once celebrating the Lord together, and this from gladness of heart. Their celebration was sometimes heard as sweet singing; for among themselves spirits and angels are possessed of a sonorous voice, and are heard by each other as well as a man is heard by a man; but human singing is not to be compared with that for a sweetness and harmony which are celestial. From the variety of the sound I perceived that there were many choirs. I was instructed by the angels with me that they belonged to the province of the lungs and to their functions; for it is theirs to sing because this is the office of the lungs. This also was given me to know by experience. They were permitted to direct my respiration, which they did so gently and sweetly, and also so interiorly, that I was scarcely sensible of any respiration of my own. I was further instructed that they who are appointed to the involuntary respiration are distinct from those who are appointed to the voluntary respiration; and I was told that they who are appointed to the involuntary respiration are present with man during sleep; for as soon as he sleeps, the voluntariness of his respiration ceases, and he receives involuntary respiration.