An investigation into the changes in the transitional church - medieval to modern
http://www.history.ufl.edu/faithful/readings/vanengen.pdf

From where do artists get their colours? 
It might seem a little strange to study art by looking at its materials. But it would not have seemed strange at all to painters of the Middle Ages or the Renaissance. They were deeply engaged with their materials, out of sheer necessity - for they made their own paints from the raw materials. These painters knew that the quality of their art depended vitally on the quality of these materials. Although that is still true today, few contemporary artists have a comparable relationship with the physical characteristics of
their medium. One suspects there is a perception almost of something vulgar about such tangible aspects of art. This means not only that some artists have undertaken illinformed and disastrous experiments with paints, but that art itself is in danger of losing touch with its roots as a practical craft – a craft that happens to have produced some of the most glorious expressions of the human spirit.

Read more here:http://philipball.co.uk/docs/pdf/RI_discourse.pdf

So why did Venice become a Renaissance city? This article suggests that the rejection of Medieval Christianity was less to do with Renaissance ideals and more connected to Venice's position as an Eastern city stuck in Europe.