Little is known about Gustave Caillebotte, who was only rediscovered in 1994 on the centenary of his death. A patron of the Impressionist movement, he painted Haussmann’s Paris, The Floor Planers, elegant passers-by sheltering under their umbrellas, and a few urban onlookers perched on balconies. We also know that he was a keen sailor, one of the world’s top regatta racers and a visionary naval architect, and that he practiced horticulture in his garden by the Seine, where he died at a young age. But above all, we remember his legacy, the Monet, Degas, Pissarro, Manet ou Renoir paintings he donated to the State in one spectacular bequest which laid the foundations for the Musée d’Orsay’s collections. Most aspects of his personality and private life elude us. His younger brother’s early death, his experience of the 1870 war, his friendships, and Charlotte, his mysterious companion – so many elements remain in the shadows. Yet for Caillebotte, painting was a reflection of life, akin to a personal diary. In this study, biographical revelations shed light on his work, leading to newfound interpretations of certain paintings. A passionate, inquisitive character emerges, wracked by anxiety and unstintingly devoted to all his passions – art first and foremost. His sense of humor and taste for social commentary also transpire. In his works, painting becomes a treasure hunt, with clues begging to be deciphered. A serious game, given that Caillebotte’s own life was no bed of roses.