Author of Key to Wisdom in the collection of Joseph Curwen. This is probably Artephius, a mystic who lived in the 12th century and wrote 'The Art of Prolonging Life,' which he was said to have written when he was 1025 years old.
("The Case of Charles Dexter Ward")
Artephius's Secret Book on creating the Philosopher's Stone and other works on alchemy can be found in the Miskatonic Library.
See also: Key to Wisdom