Numerous orders of spirit beings function throughout the domains of the local universe that are unrevealed to mortals because they are in no manner connected with the evolutionary plan of Paradise ascension. In this paper the word “angel” is purposely limited to the designation of those seraphic and associated offspring of the Universe Mother Spirit who are so largely concerned with the operation of the plans of mortal survival. There serve in the local universe six other orders of related beings, the unrevealed angels, who are not in any specific manner connected with those universe activities pertaining to the Paradise ascent of evolutionary mortals. These six groups of angelic associates are never called seraphim, neither are they referred to as ministering spirits. These personalities are wholly occupied with the administrative and other affairs of Nebadon, engagements which are in no way related to man’s progressive career of spiritual ascent and perfection attainment.
--Presented by a Melchizedek acting by request of the Chief of the Seraphic Hosts of Nebadon; from the Urantia Papers.