This book, first published in 1677, was the result of thirty years practice. It is also one of the earliest astro-medical treatises in the English language. Using the terminology of his day, Saunders speaks of humors and winds, of conditions hot, cold or dry, of the cholerick and melancholy, etc. This is a comprehensive and demanding text on medical astrology. Included are rules for decumbiture charts, illnesses produced by the traditional planets in the various signs of the zodiac, when to administer medicines based on planetary hours, and much more.