A small tiré à part extracted from the Mélanges de Science Religieuse, 1950. The Ordo referred to in the title of Joseph Daoust's interesting article is Huysmans' copy of the Ordo divino Officii peragendi in Abbatia S. Petri de Solesmis...pro AD 1900, a liturgical manual that prescribes the various offices and masses, together with the saints or holy figures in whose name they are celebrated. During Huysmans' first year at Ligugé he attended the services and made comments and notes about what he thought of the services, which were by no means always favourable, in his copy of the book, which is now in the Bibliothèque de l'Arsenal in Paris. The plaquette also includes a photo of one of the annotated pages of the book.