Bloodletting was one of the longest-lasting medical practices in human history, used for more than two thousand years across Europe, the Middle East, and parts of Asia. To modern readers it sounds brutal and irrational, but for most of history it was considered logical, scientific, and even life-saving. The practice was rooted in humoral theory, a medical framework developed in ancient Greece and later expanded by physicians such as Hippocrates and Galen. According to this theory, the human body