This article concerns information issued at the ECOM Conference in Madrid held in 1972. The Louvre Museum is discussed regarding the lighting systems in the various galleries and salons as well as the lighting used for the Mona Lisa. In order to show off paintings to their fullest and to leave the empty panels in shadows, lighting was used that had very concentrated beams that were cut up in minute fashion by diaphragms in order to perfectly show off the contour of each work. The source of light was a minuscule incandescent lamp having an iode cycle of 100 watts. The distance of the light sources in relation to the paintings is long enough that the volume of infrared rays hitting the paintings is negligible. It should be emphasized that this sort of procedure works very well for temporary exhibitions but not for permanent lighting, particularly because of the very short life-span (about 200 hours) of the minuscule iode lamps that are used.