‘Tell me at once,’ she said, sitting down.

’I have discovered an MS. at the library of the Arsenal this morning that no one knew anything about.’

He said this with an air of triumph, as though the achievement were of national importance.  Susie had a tenderness for his innocent mania; and, though she knew the work in question was occult and incomprehensible, congratulated him heartily.

’It is the original version of a book by Paracelsus.  I have not read it yet, for the writing is most difficult to decipher, but one point caught my eye on turning over the pages.  That is the gruesome fact that Paracelsus fed the homunculi he manufactured on human blood.  One wonders how he came by it.’

Susie gave a little start, which Dr Porhoet noticed.

‘What is the matter with you?’

‘Nothing,’ she said quickly.

He looked at her for a moment, then proceeded with the subject that strangely fascinated him.

’You must let me take you one day to the library of the Arsenal.  There is no richer collection in the world of books dealing with the occult sciences.  And of course you know that it was at the Arsenal that the tribunal sat, under the suggestive name of chambre ardente, to deal with cases of sorcery and magic?’

‘I didn’t,’ smiled Susie.

’I always think that these manuscripts and queer old books, which are the pride of our library, served in many an old trial.  There are volumes there of innocent appearance that have hanged wretched men and sent others to the stake.  You would not believe how many persons of fortune, rank, and intelligence, during the great reign of Louis XIV, immersed themselves in these satanic undertakings.’

Susie did not answer.  She could not now deal with these matters in an indifferent spirit.  Everything she heard might have some bearing on the circumstances which she had discussed with Dr Porhoet times out of number.  She had never been able to pin him down to an affirmation of faith.  Certain strange things had manifestly happened, but what the explanation of them was, no man could say.  He offered analogies from his well-stored memory.  He gave her books to read till she was saturated with occult science.  At one moment, she was inclined to throw them all aside impatiently, and, at another, was ready to believe that everything was possible.

Dr Porhoet stood up and stretched out a meditative finger.  He spoke in that agreeably academic manner which, at the beginning of their acquaintance, had always entertained Susie, because it contrasted so absurdly with his fantastic utterances.