Now let us study an actual example, and for the purpose I have chosen Raphael’s _Disputá_.[1] It is painted on a wall of one of the “Stanze” or suite of rooms in the Vatican, the home of the Pope, in Rome. Raphael painted many other decorations in these rooms, but this was his first one, executed when as a young man of twenty-five he had been summoned from Florence to work for the powerful pope, Julian II. Raphael had been a pupil of Perugino, and he took one of the geometrical designs that his master had already used. The pupil, however, improved upon it.