Background: The concept of pneuma—originating in ancient Greek philosophy as a vital force linked to breath and life—played a fundamental role in early medical theories, particularly in cardiopulmonary physiology. This study explores the historical evolution of pneuma, tracing its influence from pre-Socratic thought to modern medical science. Methods: A comprehensive historical analysis was conducted through a systematic review of primary texts from ancient medical and philosophical traditions, including works by Hippocrates, Aristotle, Galen, and medieval Islamic scholars. Secondary sources were examined to assess the transformation of pneuma as scientific discoveries advanced the understanding of respiration and circulation. Results: Pneuma was initially regarded as a life-sustaining force responsible for circulation, respiration, and neural function. It was central to Hippocratic and Galenic medicine but began to lose scientific validity with Ibn al-Nafis’s discovery of pulmonary circulation and William Harvey’s demonstration of systemic circulation. The identification of oxygen by Joseph Priestley and Antoine Lavoisier in the 18th century led to the final displacement of pneuma as a physiological concept. Conclusion: The historical trajectory of pneuma illustrates the transition from speculative medical theories to empirical science. While no longer relevant in modern physiology, pneuma has left an enduring legacy in medical terminology and holistic perspectives on health, highlighting the deep connections between ancient and contemporary medical thought.