There were the principal and the most obscure treatises on Alchemy or Astrology, on Magic; old Latin volumes most of them. Here were books about Witchcraft, Diabolical Possession, "Fascination" or the Evil Eye, here comments on the Kabbala. Ghosts and Apparitions were a large family. Secret societies of all sorts hung on the skirts of the Rosicrucians and Freemasons, and so found a place in the collection. Then the semi-religious, semi-occult, semi-philosophical sects and schools were represented: we dealt in Gnostics and Mithraists, we harboured the Neoplatonists, we conversed with the Quietists and the Swedenborgians. These were the ancients, and beside them were the modern throng of Diviners and Stargazers and Phychometrists and Animal Magnestists and Mesmerists and Spiritualists and Psychic Researchers.He neglected to mention, says Aaron Worth in the Dec 20 TLS, his volumes on history, geography, anthropology, and physiognomy, not to mention what was said to be a large collection of pornography.
Machen always said that made writing "literature" was contact with "ecstasy": "substitute is you like rapture, beauty, adoration, wonder, awe, mystery, sense of the unknown." This view that did not impress the young D.H. Lawrence:
Machen says that the touchstone of art is ecstasy – whatever that may be. I think he means crying about the mysteries.