The 19th century looks at work as an effort susceptible of division into measurable segments, each of which can be remunerated. What then is the legitimacy of literary work, executed outside the industrial organisation, and at home ? There are two possible responses : the vindication of literary work as a value and as a process which is partly mechanical and can thus find its place within an industrial and media regime, and be legitimately remunerated, or the preservation of its sacred nature. Writers’ambivalent relationship to nocturnal work, a compromise between what is measurable ad what is sacred, is a way into the understanding of the psychological and socio-economic problematic all modern writers, from Balzac to the Goncourts through Daudet, are tied into. It also enables the evaluation of the critical efficacy of literary “chronometry”.