This book is an English translation of Book 16 of the Astrologia Gallica. In the First Section, Morin explains the difference between Rays and Aspects, and he then discusses the natures of the aspects, why some of them are good and others bad, and finally he proposes a rational theory of the orbs of the aspects. The Second Section is devoted to Applications and Separations and Doryphories. The Third Section discusses the topic of Combustion with examples from Morin's own horoscope. Morin was a physician who became the most renowned of all French astrologers. He was appointed Royal Mathematician to King Louis XIII and was summoned to be present at the birth of the royal heir, the future King Louis XIV. James Herschel Holden is Research Director of the American Federation of Astrologers and has been especially interested in the Morin Method of horoscope interpretation.