Sephirah

The nine choirs of angels (seraphim, cherubim, thrones, dominions, virtues, powers, principalities, archangels and angels), are the ranks of the celestial hierarchy in Christian angelology, arranged in three triads of three. The seraphim, nearest to God, burn with love; the lowest choirs, the archangels and angels, are those most concerned with human affairs.

The ordering comes from the Celestial Hierarchy attributed to Dionysius the Areopagite, a work of around the fifth or sixth century, and was taken up by later theologians such as Thomas Aquinas, becoming the standard scheme of Western Christian thought about the angels.

The hierarchy expresses a Neoplatonic vision of graded being: the divine light passes down through the ranks, each choir receiving illumination from those above and transmitting it to those below, with the highest contemplating God directly and the lowest carrying out his errands in the world. The scheme influenced medieval cosmology, art and the mapping of the heavens.

The atlas gives each choir its rank, its nature, and its function in the hierarchy. The archangels, who form one of the nine choirs but are treated as major figures in their own right, and the wider hosts of spirits, are treated in their own categories.