`` `` the appearances , which are by this simple instrument rendered so obvious , may be easily inferred from the established laws of perspective ; for the same object in relief is , when viewed by a different eye , seen from the two points of sight at a distance from each other equal to the line joining the two eyes . yet they seem to have escaped the attention of every philosopher and artist who has treated of the subjects of vision and perspective . '' ''
C0015392
eye
C0042789
visio