Rik Wouters made this watercolor painting, Nightmare – War, most likely during the First World War. You can see how the wide, horizontal brushstrokes of color evoke a landscape or a seascape, but one that’s turbulent, almost apocalyptic. The materiality of watercolor is so crucial here. It's thin and translucent, creating layers of color that blend and bleed into each other, like the sky weeping. Look at how the blues and reds dominate, creating a sense of unease and tension. See the way Wouters allows the colors to mix and run, creating these unpredictable effects. There is a passage with some green, but it’s an unsettling shade – like sickly algae. Wouters died young, in his early thirties, during the war. This piece reminds me of some of the expressionistic landscapes by Emil Nolde, but with a more feverish and haunted feel. It's a reminder that art can capture the unspeakable and give form to our deepest fears.