Inscrutable applies to that which is. This is reminiscent of the extraordinary relationship which amputees develop with their artificial replacements, revealing a whole inner mysterious. See examples of mysterious used in a sentence.
Russia’s Return to the Middle East Ústav mezinárodních vztahů
Full of, characterized by, or involving mystery. He died in mysterious circumstances. Someone or something that is mysterious is strange and is not known about or understood.
That which is mysterious, by being unknown or puzzling, excites curiosity or awe:
How to use mysterious in a sentence. The meaning of mysterious is of, relating to, or constituting mystery.