A significant 17th-century medical compendium gathering the practical writings of Baldassare (Balthasar) Timäus von Güldenklee (1600–1667), personal physician to the Elector of Brandenburg. This first collected edition compiles over three decades of his clinical experience, recorded in sections titled Casus & Observationes Practicae, Descriptiones Medicamentorum Singularium, Epistolae & Consilia, and Responsa Medica. Presented in clear, scholarly Latin, the work surveys 36 years of case histories, diagnostic notes, and pharmacological observations—providing a rare window into 17th-century medical theory and therapeutics. Subjects include fevers, head and nerve disorders, gynecological illnesses, epidemic and pestilential diseases, and dietetics. Timäus’s writings embody the transitional era between Galenic humoral medicine and empirical practice, with detailed commentary on drug formulations and the preparation of compound remedies. BOOK DETAILS: Leipzig: Impensis Christiani Kirchneri, 1677. First Edition. Contemporary full vellum, sewn on raised cords, yapp edges; hand-lettered spine faint but legible. RARITY ANALYSIS: This book is extremely rare. USTC (2617780) lists only two extant copies in the world's libraries. No copies have sold at auction in the last century (RBH). An enduring source in early medical literature, this 1677 Leipzig edition was printed by Christian Kirchner, one of the period’s major medical publishers. The title pages are printed in striking red and black, and the text is richly ornamented with woodcut initials, headpieces, and decorative tailpieces. The dedication to Anna Sophia Klitzing and the letter from Gvernerus Rolfincius highlight Timäus’s scholarly circle and the recognition his clinical insights received across Europe. The book’s substantial vellum binding and clean typography mark it as a serious practitioner’s volume—a synthesis of practice and humanistic medicine from the early Enlightenment. Very good for age. Vellum lightly darkened with some mottling and natural age toning; binding tight and square. Occasional light foxing and browning typical of 17th-century paper. Interior remarkably clean and crisp, margins generous. Minor contemporary ink annotations to preliminary leaves; ownership note and bookplate of D. M. L. Labrigue.