William of Conches, a pupil of Bernard's, devoting himself to psychological and physiological questions, was of less importance for the specific logico-metaphysical problem.
Feuillet des Conches Louis X VI., Marie Antoinette et Madame Elisabeth, lettres et documents inedits (6 vols., Paris, 1864-1873), while most of the works on Marie Antoinette published before the appearance of Arneth's publications (1865, &c.) are based partly on these forgeries.
To the second volume he appended a critical study on Marie Antoinette et Louis XVI apocryphes, in which he proved, by evidence drawn from documents in the private archives of the emperor of Austria, that the letters published by Feuillet de Conches (Louis XVI, Marie Antoinette et Madame Elisabeth, 1864-1873) and Hunolstein (Corresp. inedite de Marie Antoinette, 1864) are forgeries.
The churches of Conches (15th or 16th century) and of Rugles (13th, 15th and 16th centuries), and the château of Beaumesnil (16th century) are also of architectural interest.
Feuillet de Conches must be used with caution (see the bibliographical note to the article Marie Antoinette).
