inscrutability

plural inscrutabilities

1. uncountableThe condition of being inscrutable

   The inscrutability of all this was the kind of inscrutability you have when you suddenly enter a room where a furious argument has just ended. Everyone is quiet. No one is talking.

   1974, Robert M[aynard] Pirsig, Zen and the Art of Motorcycle Maintenance: An Inquiry into Values, New York, N.Y.: William Morrow & Company, →ISBN

   1 more example

   What about Mrs. Cavendish? I watched her as she sat at the head of the table, graceful, composed, enigmatic. In her soft grey frock, with white ruffles at the wrists falling over her slender hands, she looked very beautiful. When she chose, however, her face could be sphinx-like in its inscrutability.

   1920, Agatha Christie, The Mysterious Affair at Styles, London: Pan Books, published 1954, page 57

2. countableSomething that is inscrutable.

   the inscrutabilities of advanced mathematics