Paul's argument that “idols are nothing" was, in the middle ages and renaissance, often taken to mean that idols are mythical creatures, like centaurs. But Paul was also sometimes taken to mean that idols are without substance. In this line of thinking, air (rather than centaurs and other composite creatures) became emblematic of the nothingness of the idol. This had consequences for painting. For, when Alberti turned pictures into windows, he turned air, which is to say nothingness, which is to say the idol, into the matrix of painting. From this vacuous substance, painters could then conjure anything they wished, but what they conjured would always remain tainted by the the airy stuff from which it was made.
With generous funding from the Andrew W. Mellon Foundation