The observer, he says, gives the facts as he has observed them, fixes the starting-point, lays the solid ground on which his characters are to walk and his phenomena to develop.  Then the experimentalist appears and starts the experiment, that is to say, he makes the personages in a particular story move, in order to show that the succession of events will be just what the determinism of phenomena together with study demand that they should be.  The author must abstain from comment, never show his own personality, and never turn to the reader for sympathy; he must, as Mr. Andrew Lang has observed, be as cold as a vivisectionist at a lecture.  Zola thought the application of this method would raise the position of the novel to the level of a science, and that it would become a medium for the expression of established truths.  The fallacy of the argument has been exposed by more than one critic.  It is self-evident that the “experiments” by the novelist cannot be made on subjects apart from himself, but are made by him and in him; so that they prove more regarding his own temperament than about what he professes to regard as the inevitable actions of his characters.  The conclusion drawn by a writer from such actions must always be open to the retort that he invented the whole himself and that fiction is only fiction.  But to Zola in the late sixties the theory seemed unassailable and it was upon it that he founded the whole edifice of Les Rougon-Macquart.  The considerations then that influenced Zola in beginning a series of novels connected by subject into one gigantic whole were somewhat various.  There was the example of Balzac’s great Comedie Humaine; there was the desire of working out the theories of heredity in which he had become interested; there was the opportunity of putting into operation the system which he had termed naturalisme; and there was also the consideration that if he could get a publisher to agree to his proposals he would secure a certain income for a number of years.  His original scheme was a series of twelve novels to be written at the rate of two a year, and he entered into a contract with a publisher named Lacroix, who was to pay him five hundred francs a month as an advance.  M. Lacroix would, however, only bind himself to publish four out of the twelve novels.  The arrangement could not be carried out, and at the end of three years only two volumes of the Rougon-Macquart series had been published, while Zola found that he had become indebted to the publisher for a very considerable sum.

The first novel of the series was begun in 1869, but was not published till the winter of 1871, delay having occurred on account of the war with Germany.  Zola was never a rapid writer, and seems to have regulated his literary production with machinelike uniformity.  As his friend and biographer Paul Alexis writes:  “Only four pages, but four pages every day, every day without exception, the action of the drop of water always falling on the same place, and in the end wearing out the hardest stone.  It seems nothing, but in course of time chapters follow chapters, volumes follow upon volumes, and a whole life’s work sprouts, multiplies its branches, extends its foliage like a lofty oak, destined to rise high into the air and to remain standing in the forest of human productions.”