Early Greek theories split on vision. Extramission, backed by the Pythagoreans and by Galen in the second century AD, held that the eye emits light that illuminates objects, while intromission, supported by the Atomists and Aristotle, held that objects send images into the eye. Kepler's 1604 work explained how images on the retina are flat and upside down yet are perceived upright and in depth, and concluded the brain must do the work. Descartes in 1637 argued that what we see is a mental representation, and Helmholtz in the 1860s combined optics and physiology to show perception is shaped by the brain. Demonstrations such as the rotating mask illusion show that the brain's assumptions about faces can override what the eye receives.

Hampi is a UNESCO World Heritage Site in Karnataka, India, with more than 1,600 surviving remains spread over 4,100 hectares. It was the capital of the Vijayanagara Empire from 1336 to 1565. Travellers from Persia and Portugal described it as a prosperous, wealthy and grand city with temples, markets and farms along the Tungabhadra River. By 1500 it was estimated to be the world's second-largest city after Beijing, and probably India's richest at the time. In 1565 a coalition of Muslim sultanates defeated the Vijayanagara Empire, its capital was conquered and destroyed, and the city was left in ruins. Hampi remains a religious centre, with the active Virupaksha Temple at its heart.