Giotto is considered the “Father of the Renaissance”. Characterized as a Proto-Renaissance painter, his work is a transition from the late medieval (Byzantine, Gothic). His innovations were the use of approximate perspective (~a first in occident!), increased volume of figures, and a depth of emotion which suggests human feeling instead of static and passive icons.

Exorcism of the demons at Arezzo (1297)
Note the (clumsy) perspective! The town looks like a 20th century painting!

Lamentation Over the Dead Christ (1305)

http://en.wikipedia.org/wiki/Giotto_di_Bondone
The Heritage of Giotto’s Geometry: Art and Science on the Eve of Scientific Revolution (the use of geometry in art was a catalyst to the European scientific revolution!)