This is Robert Julius Boers’ ‘Familieportret’, a stereograph from the late 19th or early 20th century, held at the Rijksmuseum. It's a fascinating look at how photography, then and now, tinkers with our perceptions. The sepia tone is so pervasive. The whole image feels dipped in it, which renders a kind of nostalgia before its time. And then you notice that the picture is doubled in one frame. Look at the family dog sitting to the left. See how it’s there twice? It's such a basic, material fact, but it completely undermines the image's claim to authenticity. Photography purports to give us reality, but this photograph shows us the tricks of photography. Boers isn’t alone in this kind of material experiment. Think about Man Ray. The way he approached photography as a medium for messing with reality has been really important for me. I love that art embraces not knowing.