This book is an English translation of Book 16 of the Astrologia Gallica. In the First Section, Morion explains the difference between Rays and Aspects, and he then discusses the natures of 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 Horoscopes.