Though L'Assommoir may be read, enjoyed and studied perfectly well as an independent work, it must also be considered, as Zola insisted in his preface, as part of the twenty-volume series of novels, Les Rougon-Macquart (1871–93), the creation of which occupied the better part of his life as a writer. As the series subtitle suggests, The Natural and Social History of a Family under the Second Empire, it has a double design: on the one hand, the depiction of contemporary society in its various aspects, a kind of Second Empire Human Comedy; on the other hand, a representation (or exemplification) of the workings of the laws of heredity in the lives of members of a single family as they move in that society. In his preliminary notes for the series, Zola tended to emphasise the latter aim. In a page or two of jottings entitled significantly ‘Differences between Balzac and myself’, for example, he writes: ‘My work will be less social than scientific.’ But, as the series unfolded during the early years of the Third Republic, the social and historical aims tended to predominate. One essential difference between Balzac's and Zola's series is that, unlike the former's immense fresco of life in the society of the Restoration and the July Monarchy, The Rougon-Macquart, notably in L'Assommoir and Germinal, portray working-class life.