The Spirits' Book
Book Two - The Spirit World
Chapter I - Spirits
Angels and Demons
128. Do angels, archangels and seraphim constitute a special category different from that of other spirits?
“No, they are pure spirits. Those who have reached the highest degree of the ladder are all united in perfection.”
The word angel generally implies the idea of moral perfection, but it is often applied to all superhuman beings, good or bad. Therefore we say, “a good angel,” “a bad angel,” “an angel of light,” “the angel of darkness,” and so on. In those cases, it is synonymous with spirit. It is employed here in its most popular sense.