Naturalism is the literary school which, following Émile Zola, treats characters as products of environment, heredity and instinct, and describes the lives of the poor and the body without the conventions of the romantic novel. The Slum, by Aluísio Azevedo, published in 1890, is the best-known novel of Brazilian naturalism.
In the book, the method shows in the way it narrates. The narrator explains people's actions by the place where they live: the narrator says that in Jerônimo "all his simple habits of a Portuguese villager were being remade" and, further on, says that he yielded "to environmental pressures". Piedade senses the danger not through reason: "It was neither intelligence nor reason that pointed out the danger to her, but instinct".
The images come from the natural world. The tenement is born "like larvae in manure"; the residents feel "the animal pleasure of existing", like creeping plants that "plunge their vigorous feet into the black, nourishing mud of life"; the place wakes, boils and arms itself like a body. The narrator watches the crowd from outside, and after Pombinha's fate the text goes so far as to say that "the chain went on", as if the environment prepared one person after another.
The book, however, is not only thesis. The scenes show choices: Jerônimo pays the helpers who will kill Firmo and keeps the razor, João Romão does the sums before each step, and money passes from hand to hand with a precision that the outside view does not erase. Aluísio Azevedo, who had been a caricaturist, works through tableaux and crowds, and already in O Mulato, of 1881, he had brought naturalism to Brazil, with observation of the environment and the body in the manner of Zola.