Courtois' view of the function of his own drawings is known through the comments he addressed to his friend Vanghetti in a letter of September 1667, who had requested the artist to send him a study. Courtois refused, stating that he never executed drawings 'except for a few brief sketches before beginning a painting, and these are of no use to anyone but myself, because they are only ideas, and I cannot be bothered to finish them'. Baldinucci records that Courtois after making rough sketches drew directly on the canvas. This method of working explains why relatively few drawings can be directly related to paintings