Many of the features of Renaissance art depended on a change in the economic and cultural ideas influencing graphic representation. The first major shift in focus had to do with the influence of humanism. In medieval art, the point of art was anagogic, in other words, that a Byzantine icon or stained glass window in a cathedral was intended to lead the soul to God. Thus it was not meant to be a realistic portrait of some actual sensible particular, but, in the language of the platonizing theorists of the period, to imitate the forms rather than the sensibilia. Renaissance art, often commissioned by secular patrons, focused on the human world, and thus developed realistic techniques such as perspective, to more accurately represent the physical world.