Ars Angelorum by Gary St. Michael Nottingham provides a catalogue of seals and descriptions for 360 spirits who are ruled over by a series of archangels and angels. These are divided and assigned to the twelve signs of the zodiac. This grimoire provides a pathway towards self-discovery and direct contact with the angels who influence the various aspects of one's life.

From the Foreword, by David Cypher:
"... I want to share one last personal insight about these angels. Depending where you are in your personal evolution, where you are in time, what planets are transiting your houses, or who dominates, certain of the angels are louder, or more easily heard than others. Although the lesser guardian angel is the Maître 'D of your experience, they are not always the one in the driving seat. Depending on what is happening, many factors will determine which of your angels are the ones in the driving seat...." - David Cypher

From the author, Gary St. Michael Nottingham:
"To each of these degrees of the zodiac is attributed an angel, and the angel who dwells at the degree from which one's natal houses originate will be the angel who wards that particular area of one's life. However, if you do not know your birth time and cannot, therefore, work out your natal chart with any degree of certainty, you may feel that this work has nothing to offer you. If you are in this position, do not despair, as you can still work with the angel who rules the degree where the Sun is domiciled on the day of your birth. An astrological ephemeris will show the degree of the zodiac that the Sun occupied on your day of birth, as it will all other planets too. The angel of the solar degree can be petitioned for help as an alternative to working with the natal angels generally. " - Gary St.Michael Nottingham