Emission theory (vision)

[6] Some argued that Euclid's version of emission theory was purely metaphorical, highlighting mainly the geometrical relations between eyes and objects.

However, his theory of clarity of vision (the circular appearance of far rectangular objects) makes sense only if the ray emits from eyes.

Alternatively, Euclid's can be interpreted as a mathematical model whose only constraint was to save the phenomena, without the need of a strict correspondence between each theoretical entity and a physical counterpart.

In Cartesian physics, light was the sensation of pressure emitted by surrounding objects that sought to move, as transmitted through the rotatory motion of material corpuscles.

[11][clarification needed] Rupert Sheldrake claims to have found evidence for emission theory through his experiments in the sense of being stared at.

In practice some animals (bats, dolphins, whales, and even some birds and rodents) have evolved what is effectively an ‘extramission’ theory of audition to address this very concern. "