​Index Materiae Medicae: Or, A Catalogue of Simple Medicines is a seminal work in early modern pharmacology, authored by James Douglas and first published in 1724. This comprehensive catalog serves as a foundational reference for the practice of medicine and surgery, detailing a wide array of simple medicines used during that era.​

The catalog is meticulously organized, presenting each medicinal substance with its officinal Latin name, complete with accentuation and genitive case. Douglas provides concise botanical descriptions of the species commonly utilized, along with their names in Greek and English, facilitating a broader understanding across linguistic barriers. The work also identifies the specific part of the plant or substance most commonly used in medical preparations. Additionally, it lists the names of dispensatory or shop preparations and compositions associated with each substance, offering insight into the practical applications of these medicines in the field.​

To enhance usability, Douglas includes two tables: the first categorizes the simple medicines under general heads, while the second classifies them according to their principal virtues. This systematic approach not only aids in the identification and application of medicinal substances but also reflects the evolving understanding of pharmacological properties during the early 18th century.​

Index Materiae Medicae stands as a testament to the rigorous scientific inquiry of its time, bridging classical knowledge with contemporary medical practices. Its detailed classifications and comprehensive listings have made it an invaluable resource for historians of medicine and pharmacology, providing a window into the medicinal practices that laid the groundwork for modern therapeutics.​