If photonics can be defined as the practical application of light, then one of the technology’s earliest applications has been to reveal what we couldn’t naturally perceive. Fire allowed us to see in the dark. The microscope showed us the cell. The telescope showed us the planets and distant shores. Spectroscopy disclosed the molecular and chemical composition of materials. But are there cases in which our advancements may be hiding information from us? Take, for instance, the experience of Fordham University professor Edward Wachtel and his speculations around the famous cave art at Grotte de la Mouthe in southern France. Until he visited the caves in 1993, Wachtel had only seen photos of the prehistoric drawings within, which were illuminated by the bright electric flashes of modern photography. What he saw in the pictures puzzled him. The prehistoric artists had drawn what looked to him like “spaghetti lines” over their animal illustrations, partially obscuring them. Other figures featured multiple heads or had other animals superimposed over them. The art seemed crowded and clumsy. The caves themselves are massive, and space was not lacking. So why the layers? Wachtel decided that he needed to take a closer look. Guided by the light of a gas lantern held by a local farmer, Wachtel entered the caves. Along the walls were the paintings he had seen in the photographs. However, standing there in person, Wachtel realized that the flickering lamp, the irregularities of the cave wall, and the layered drawings all worked together to create a prehistoric picture show. The lines that Wachtel had seen in the photos became forests or bramble patches behind which the animals were standing. The mammoth no longer had three trunks, it was swinging its trunk from side to side. In the firelight of the lantern, the grazing ibex didn’t have a second head, it was looking up to check for predators. A paleolithic rock painting of a bison and a horse in the Cave of Altamira near Santillana del Mar in Cantabria, Spain. Courtesy of iStock.com/JESUSDEFUENSANTA. The artificial light of the camera’s flash may have lit up the images and brought them into focus, but it became clear to Wachtel that it had also left out the true depths of the artwork. He observed that the paintings had been created to take advantage of the flaming illumination sources used at the time. A recent study conducted by a team of Spanish researchers examined the sources of fuel used by prehistoric humans. The researchers found that the fireplaces in the cave that they studied in Spain’s Basque country seemed to be strategically arranged to illuminate the entire area that was decorated with artwork. The study may validate Wachtel’s theories about the art in the la Mouthe caves. It also undoubtedly draws a line connecting light and art, from prehistory to today.