Literary creativity is multi-directional. It looks backwards, sideways and forwards. A writer will follow or subvert a tradition, will be aware of what his contemporaries are doing, and will hope to surpass them. Literary historiography by contrast can only look in one direction; it is a discipline that seeks to order the past and whose understanding of that past is a function of the taxonomy employed. At its simplest, the taxonomy of the modern Spanish novel consists of a series of labels that purport to describe a succession of approaches to the writing of fictional prose. After the early nineteenth- century romances set in remote times à la Walter Scott came the more earthy yet picturesque descriptions of contemporary life of the costumbristas (portrayers of contemporary customs), which led in turn to the more ambitious plotting and complex vision of the contemporary world that characterizes realism, the dominant mode of novelistic writing in the second half of the nineteenth century. The concomitant rise of science and the emergence of the quasi-scientific discipline of sociology persuaded some novelists to attempt to follow the example of the Frenchman Émile Zola and emulate the natural sciences by converting the novel into a tool for the seemingly scientific study of society and its ills. Naturalism was in effect a pseudo-scientific form of realism. The late nineteenth-century disillusionment with science because of its perceived failure to solve the growing social conflicts of rapidly industrializing societies led naturalism into disrepute; in Spain, rather than producing a novelist of the rank of Zola, it had spawned a vast number of second-rate novels obsessed with the seamier sides of life: sex, alcoholism, crime, and moral and environmental decay. It was against the materialism of naturalists that older realists like Benito Pérez Galdós and Emilia Pardo Bazán reacted, in their later more spiritually driven work, as did a new generation of younger writers (Clarke 1999: 3–17). In this chapter we shall consider the work of four novelists all born within ten years of one another, between 1864 and 1873, and all of whom produced work of lasting influence: Pío Baroja, Miguel de Unamuno, Ramón del Valle-Inclán, and Azorín. These four writers can be considered the advance guard of a movement whose radical novelty would not become apparent until after World War i and which reached its climax in the avant-garde writers of the 1920s (Lough 2000: 39–41.