“Galen and Paracelsus” by J.C. Dalton, published in 1873, offers a comparative study of two influential figures in the history of medicine. Galen, a Greek physician of the 2nd century, was instrumental in shaping medical understanding through his theories on anatomy and the four humors. Paracelsus, a 16th-century Swiss physician and alchemist, challenged these traditional views, advocating for a more empirical and chemical approach to medicine.

Galen’s medical philosophy was rooted in the balance of four bodily fluids: blood, phlegm, yellow bile, and black bile. He believed that an imbalance among these humors led to disease, and treatments like bloodletting and purging were common practices to restore equilibrium. His work synthesized earlier Greek medical knowledge and remained authoritative for over a millennium.

In contrast, Paracelsus rejected the humoral theory, proposing that diseases were caused by external agents and could be treated with specific chemical remedies. He introduced the use of minerals and chemicals in medicine, emphasizing the importance of dosage with his famous assertion that “the dose makes the poison.” Paracelsus’s approach laid the groundwork for modern pharmacology and toxicology.

Dalton’s book highlights the transition from Galenic to Paracelsian medicine, illustrating the evolution of medical thought from a focus on bodily fluids to a chemical understanding of disease. This shift marked a significant turning point in medical history, leading to more scientific and experimental methods in diagnosing and treating illnesses.