The third volume of The Seven Books of Paulus Ægineta, translated by Francis Adams, delves into the properties and classifications of medicinal substances, both simple and compound, as understood in ancient Greek, Roman, and Arabian medical traditions. This volume serves as a comprehensive guide to the Materia Medica and Pharmacy of the ancients, offering insights into the therapeutic qualities of various substances and their applications in medical practice.​

The text categorizes medicinal substances based on their temperaments, primarily focusing on their heating and cooling properties. It emphasizes the importance of taste as a diagnostic tool, asserting that the flavor of a substance can reveal its medicinal qualities. For instance, substances that are sweet are considered to relax and soften, while those that are bitter are believed to cleanse and purify. This approach reflects the ancient understanding of the balance of humors and the need to restore harmony within the body.​

In addition to discussing individual substances, the volume explores the preparation and application of compound medicines, including purgatives, emetics, and antidotes. It provides detailed instructions on the formulation of these compounds, highlighting the significance of dosage and administration methods. The text also addresses the management of patients undergoing treatment, offering guidance on the appropriate use of medicinal substances to achieve optimal therapeutic outcomes.​

The volume includes an appendix that introduces substances incorporated into the Materia Medica by Arabian physicians, reflecting the integration of diverse medical knowledge. This inclusion underscores the evolving nature of medical practice and the exchange of ideas across cultures. Overall, the third volume of Paulus Ægineta’s work provides a detailed and systematic account of ancient medicinal practices, serving as a valuable resource for understanding the foundations of pharmacology and therapeutic interventions.