Isaiah 6:2

Above it stood— The state, figure, and actions of the Seraphim are here described: The word שׂופים seraphim, says Vitringa, signifies fiery and shining bodies, from ףּשׂר seraph, to burn; (see Numbers 21:6.) and is in this place to be understood of persons of a bright and splendid appearance, covered with wings, and in a human form. This part of the vision seems manifestly to be taken from the representation of the Divine Glory, as it was exhibited in the Holy of Holies; where was the mercy-seat, and the cherubim representing the Divine Majesty, attended with the angelic host; and thus also the fourth verse refers to the temple, and the priest offering up the incense, more especially when he entered into the Holy of Holies. This passage, mystically understood, represents the future dominion of Christ as Mediator, and the diffusion of his gospel through the world by his messengers and ministers; the filling the earth with his glory, and spreading throughout the world the merits of his divine intercession. For a large and learned application of each particular the reader is referred to Vitringa.