Machen, Arthur: The Novel of the Black Seal. v1. 8 Mar 2013
 

Arthur Machen : 3 March 1863 – 15 December 1947) was a Welsh author and mystic of the 1890s and early 20th century. He is best known for his influential supernatural, fantasy, and horror fiction. His novella The Great God Pan (1890; 1894) has garnered a reputation as a classic of horror. (Stephen King called it "Maybe the best [horror story] in the English language".) He also is well known for his leading role in creating the legend of the Angels of Mons.

Excerpt
'I see you are a determined rationalist,' said the lady. 'Did you not hear me say that I have had experiences even more terrible? I too was once a sceptic, but after what I have known I can no longer affect to doubt.'