Conrad Rudolph said this quote

“ [Medieval] Art was not just a static element in society, or even one which interacted with the various social groups. It was not simply something which was made to decorate or to instruct — or even to overawe and dominate. Rather, it was that and more. It was potentially controversial in ways both similar and dissimilar to its couterpart today. It was something which could by its force of attraction not only form the basis for the economy of a particular way of life, it could also come to change that way of life in ways counter to the original intent. Along with this and because of this, art carried a host of implications, both social and moral, which had to be justified. Indeed, it is from the two related and basic elements of justification and function — claim and reality — that Bernard approaches the question of art in the Apologia. ”