The stained glass artist Patrick Reyntiens mentions "Claritas":-
".. a quality of visuality which in the Middle Ages has
an importance far from being appreciated today. The visual quality of reflection and transparency was an indication
of a higher, moral, order, an order which was the beginning of the ultimate reality which, in a word, reflected
heaven. It was the most highly prized of medieval visual qualities … the main quality sought was one of uplift
to the eye and therefore to the spirit, using transparency, translucency and multiple reflection."
Patrick Reyntiens: "The Beauty of Stained Glass" London, 1988