The Enigma
The Enigma is the mystical focus and Outer Mystery of House Criamon, as described in ArM5 92. It provides access to the Enigmatic Wisdom Ability, and forms the foundation of the House's mystical teachings.
The Enigma is left intentionally vague in the fifth edition core book, as well as in all prior edition material. It is, however, thoroughly explained in HoHMC. See House Criamon.
Also the Virtue of this name, signifying initiation into the Outer Mystery of the Enigma.