The fourth and final book in Louis Couperus' Books of the Small Souls quartet. Ten years have passed since the conclusion of The Twilight of Souls. Constance and Henri van der Welcke have moved into the van der Welcke family home at Driebergen. Living with them in the dark and gloomy house are Mamma van Lowe, Constance's niece, Emilie, daughter-in-law, Mathilde, and her two young children, together with brother Gerrit's wife Adeline and their 'flaxen-haired tribe' of nine children. As the book opens, the household is keenly anticipating the return of Mathilde's new husband Addie, now Dr, Adriaan, who is kept busy not only by his practice but also by his responsibilities to his growing family. - Summary by Philip Benson Dr Adriaan - Het Helige Weten - https://librivox.org/het-heilige-weten-van-louis-couperus/