The Last Supper is regarded as one of the supreme masterpieces in the whole field of pictorial  art. Tradition has it that Leonardo Da Vinci worked for ten years upon the painting, the monks in the church annoyed at the delay. It was said that Leonardo often painted continuously from dawn to night without eating his meals. But at other times he spent hours before the picture, lost in contemplation, examining, comparing, and measuring his figures. This inactivity aroused the anger of the fussy Prior , the head of the church, who belonged to the large group of those who believed that the busier a man seems, the more he accomplishes; and so he tried to find fault with the idle painter. Leonardo was slightly unhappy and explained to somebody else that there is a great difference between the work of the creative artist and the stonemason. The creative artist needs time for contemplation; he may be busiest when his hands are idlest. Just now he needed two heads to complete the picture: that of Christ, for which no model on earth could be found, for where was the man to be found whose face would express the strength, and beauty, and tenderness, and deep sorrow of the Christ; then he also needed a head of Judas, and that was hard to find as well, for where was the man whose face could express the meanness of that base  traitor . But he would look no further; if none came his way, he would be satisfied to take Prior as a model for Judas. This threat silenced the angry Prior, who quite naturally had no desire to pass to descendants  in such a fashion. Why did the prior stop complaining?
He did not wish to be remembered like an evil traitor after he died. He wanted to be painted as Judas who betrayed his master. He disliked to be painted in fashionable clothes. He was pleased to be a fashionable model.