World From Top, By Klaus Lerdorf

• Parmenides
The traditional interpretation of Parmenides' work is that he argued that the every-day perception of reality of the physical world (as described in doxa) is mistaken, and that the reality of the world is 'One Being' (as described in aletheia): an unchanging, ungenerated, indestructible whole.
• Plato
In his Allegory of the Cave, Plato distingues between forms and ideas and imagines two distinct worlds : the sensible world and the intelligible world.