In accounts of the development of naturalism in fifteenth-century painting, linear perspective is usually given first consideration. This modern emphasis on perspective has been influenced, no doubt, by the writings of the fifteenth-century artists themselves. Discussions of it occupy a prominent place in the treatises of Alberti and Piero della Francesca. But these discussions were motivated not only by a sense of the importance of perspective for painting, but also by a desire to raise the status of the craft, and a corresponding insistence on the theoretical and mathematical modes of thought necessary to it.