Against Nature, also known as Against the Grain, is a novel by Joris-Karl Huysmans that epitomizes the decadent movement of the late 19th century. The protagonist, Jean des Esseintes, is a wealthy and eccentric aristocrat who retreats from society to indulge in his own aesthetic and sensual pleasures. The book explores themes of artificiality, hedonism, and the rejection of traditional values. Huysmans' vivid descriptions and meticulous attention to detail create a rich and immersive reading experience that captures the essence of the fin-de-siècle period.