Optics (Ptolemy)

[4] Eugene's text was influential in the late medieval and Renaissance-era development of optics, even though its importance was overshadowed by the publication of the Latin translation of Alhazen's De aspectibus at the turn of the 13th century.

The work contains the earliest surviving table of refraction from air to water, for which the values (with the exception of the 60° angle of incidence), although historically praised as experimentally derived, appear to have been obtained from an arithmetic progression.

Size and shape were determined by the visual angle subtended at the eye combined with perceived distance and orientation.

This was one of the early statements of size-distance invariance as a cause of perceptual size and shape constancy, a view supported by the Stoics.

[7] Ptolemy offered explanations for many phenomena concerning illumination and colour, size, shape, movement and binocular vision.

He offered an obscure explanation of the sun or moon illusion (the enlarged apparent size on the horizon) based on the difficulty of looking upwards.