It's all about vaishing points, which artists have employed going back before Albrecht Durer, but not too much further than Durer. Prior to Michelangelo who was just a generation ahead of Durer, everything seemed *flat* and perspctive was either not important or figured out.

Speaking of perspective, Durer's woodcut "Demonstration of Perspectivde" (circ 1525) suggests that artist were just getting it as he depicts an artist using a string to assist in setting up a perpective.

Ouch, that hurt...

Bobert