In ancient philosophy, the theory that vision occurs when light rays are emitted from the eye to the object being seen, rather than light entering the eye.
From Latin 'extra' (outside) + 'mittere' (to send). This was the dominant theory of vision in ancient Greece and Rome, proposed by thinkers like Euclid and Galen.
Brilliant scientists got this backwards for 1,500 years—they thought your eyes shot out invisible beams that 'felt' objects like fingertips. Algebra and geometry were built on this wrong assumption about how light works, yet the math still worked out.
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