Isaiah 6:2

Isaiah 6:2. Above it stood the seraphims: each on had six wings; with twain he covered his face, and with twain he covered his feet, and with twain he did fly.

There are the spirits that dwell in the presence of God, nearest to him, and as he is a consuming fire they come to be like him, for the seraphims are burning ones, consumers, burning and shining lights, who wait upon God, who is light of life. Notice how humble they are in that presence; they cover themselves before that Infinite Majesty.