This chapter takes up Zola’s self-portrait as Saint Thomas in the wake of his much-commented visit to Lourdes in 1892. The novel he went on to write about the Pyrenean shrine, ‘that divine land of dreams’, was largely based on those supposedly miraculous events he had witnessed, and about which he remained sceptical. This chapter looks to Zola’s Lourdes (1894), in conjunction with the heated polemic it provoked, to better understand the stakes of the author’s divisive foray into matters of Catholic practice and dogma. More than an expression of Zola’s anti-clericalism, the novel aroused debates that were aesthetic as much as ideological, as adversaries argued over questions of representation, proofs, facts, documents, and faithfulness. The chapter reads a set of material penned by Catholic detractors, who were determined to defend the divine status of the miracle, casting Zola’s naturalism as an illegitimate, unbelievable – even, à la limite, idealist – aesthetic mode.