In this relief we can see a strong emphasis of the contoured lines articulating a dramatically turning pose and the modelling of the bulging muscles demonstrates the impact of Michelangelo on the artist's work. In learning from Michelangelo, Raphael is also rivalling him. The fundamental principle of all the arts in Florentine eyes, the artist demonstrated his virtue through his visions which was understood as "the solving of difficult problems and the treatment of new problems achieved by a lively intelligence." Artists challenged themselves to present the human body in complex poses. By doing this they overcame diffculty. The fluid movement or grace of these figures also speaks of the artist's demonstration of sprezzatura, which is the apparently effortless resolution of difficulty. Sprezzatura was identified by Baldesar Castiglione in his Book of the Courtier as one of the attributes of a refined courtier.