With pen and ink, Ingres illustrates how window light would shine on a figure. "...although the daylight comes from the right side of the painting, the daylight coming from the left side should not be dismissed. If this is the case, all the charm of the brush work will be lost...." He sketches a figure from the back with one foot on a step, SIGNED "Ingres. The letter is significant because it reveals the working artist considering the affect of light on a subject. He draws two lines of light as they might contact the figure as he describes. Ingres would occasionally use pen and ink to sketch first ideas, but in this instance, it would seem that he used the pen to write the letter and illustrated his meaning with the drawing. The text suggests he may have been giving advice to another artist or student rather than sketching a preliminary drawing for his own work. Condition: Docketing in upper left corner in red in another hand, sunning around margins likely from prior framing, slight chipping on right margin and slight soiling at center fold. The illustrated letter measures 5.25 x 8 inches and floats on a dark gray mat overlaid with a white mat, framed in black satin finished wood, matted and framed in museum quality materials, framed in 5/8/inch black satin wood. Frame measures 12.5 x 15.75.