Chest Tightening at High Altitude Al-An'am

The Quran reaches for a simile to describe spiritual misguidance, and the one it chooses is climbing skyward: 'He makes their chest tight and constricted, as if they were climbing up into the sky.' The simile is anatomically exact. At high altitude, decreasing atmospheric pressure reduces oxygen availability, causing dyspnea and chest tightening, precisely the sensation the verse describes. The Quran is not offering this as a scientific observation but as a vivid metaphor, implying its listeners would already recognise the feeling. What they could not have known is the mechanism behind it. The physiological effect of altitude on breathing was not scientifically explained until the 18th century, through the work of atmospheric scientists. The Quran reached for it as an image fourteen centuries earlier.