Aristotle (c. 384-322 BC) and size-distance invariance
In his book on Memory, Aristotle takes the comparison of the sizes of objects at different distances as an analogy of the comparison of time periods. He seems to be referring to the theory of size-distance invariance â€“ that we take account of distance in a kind of geometrical manner when judging size. He proposed that there was a mental representation of the outside world, as distinct from a knowledge of distance brought by the travelling visual ray. He held to a concept of geometry that was developed from Pythagoras onwards and flourished later among the Stoics. This may be the earliest known reference to size-distance invariance.