In planning his 1888 Le Rêve, Zola envisaged a novel that would be distinctly out of character: ‘je voudrais faire un livre qu’on n’attende pas de moi’. The present article explores what is at stake in Zola’s desire to break with his own image at this juncture in the history of naturalism’s reception. While Le Rêve can be understood as a demonstration of the author’s versatility in the face of new strains of aesthetic experimentation in the aftermath of the ‘Manifeste des Cinq’, it also responds to a more longstanding negotiation with the language of idealism. The article focuses on Zola’s harnessing, and critique, of the idealist imagination in Le Rêve. It first proposes a psychoanalytical reading of the Zolian heroine’s fantasy life through the lens of Freud’s 1908 ‘Family Romances’. The child’s power to redraw reality through day-dream – to enact what Freud terms ‘a correction of actual life’ – is connected, in turn, to the wager that frames Zola’s narrative: that of rendering ‘la vie telle qu’elle n’est pas’. Zola’s experiment with idealism thus involves rehearsing the terms and suspicions at work in his earlier biographical writing on George Sand – the idealist writer Zola had assimilated to the ‘dream’ of the novel’s title.