La Religieuse (also called The Nun or Memoirs of a Nun) is an 18th-century French novelby Denis Diderot. Completed in about 1780, it was first published by Friedrich Melchior Grimmin 1792 (eight years after Diderot's death) in his Correspondance littéraire in Saxony, and subsequently in 1796 in France.

The novel began not as a work for literary consumption, but as an elaborate practical joke aimed at luring the Marquis de Croismare, a companion of Diderot's, back to Paris. The novel consists of a series of letters purporting to be from a nun, Suzanne, who implores the Marquis to help her renounce her vows, and describes her intolerable life in the convent to which she has been committed against her will.^[1][2]

In 1758, the Marquis involved himself in a controversial case where a nun, Marguerite Delamarre, was trying to be dispensed from her vows and return to society. The Marquis pitied Marguerite and unsuccessfully tried to use his political influence to liberate her. After losing the case in 1758, Marguerite was forced to remain in the convents for the rest of her life. Diderot used Marguerite Delamarre as a prototype for Suzanne, thinking Croismare would be persuaded to return to Paris in order to save Suzanne from her misery in the convent.^[3]

Eventually, this practical joke turned into a passionate project for Diderot, in which he self-identifies as a woman.^[4] Diderot later revised the letters into a novel depicting corruption that was supposedly rampant among the clergy and in religious institutions. When Diderot publicly admitted his role in the ruse, the Marquis is said to have laughed at the revelation, unsurprisingly since he had behaved with exemplary compassion and generosity in his willingness to help the imaginary Suzanne.^[1]