Mystery (神秘, Shinpi?) is a sliver of power of many different types that comes from the Root. It is the source of all supernatural phenomena such as Magecraft or ESP, and beings such as True Ancestors, Servants, Spiritual Bodies, as well as Phantasmal Species are formed entirely of Mystery. If multiple people attempt to use the same type of Mystery, such as in the case where the general public becomes aware of Magecraft, the Mystery itself will weaken and die out.
If two different types of Mysteries collide with one another, the stronger Mystery will overwhelm the weaker one. However, this does not necessarily mean that the user of the stronger Mystery will be stronger than his opponent. For example, for Heroic Spirits, it is usually the case that a Heroic Spirit of the Age of the Gods will have a higher Mystery, but a Heroic Spirit of the Age of Man will have higher fame due to clarity in history. There are, however, exceptions to this rule, such as with Achilles.
Merlin reveals in Garden of Avalon that planets change their laws of physics according to the kinds of creatures living on its surface, and because mankind became the dominant species on Earth, the Mystery of the gods, taking the form of Magecraft, slowly disappeared, and the Age of the Gods ended entirely with Solomon's death. Uniquely, however, Britain still retains some of the gods' Mystery due to being the "navel of the Earth" that connects the World to the Reverse Side of the World.
Certain items that have a long history and age can also show signs of Mystery, as in the case of the centuries-old katana that the Ryougi possess, Kanesada Kuji. If they are severely damaged, however, they will lose all the Mystery they have accumulated.
- ↑ All the different disciplines and paradigms of learning magecraft flow from this single, indivisible source. - Kara no Kyoukai Chapter 5: Paradox Spiral
- ↑ They do this because the fact that a mystery is a mystery grants it a value and meaning. Reality deals with beliefs. Enough people believe that magic is gone, almost dead, and so it is. The fact that magi know this, and yet pursue their craft is what gives them the power to reshape reality to their will. In the most crippling paradox for magi, they cannot allow Magecraft to die, and yet too many magi will deaden it, make it mundane. Without the mystery and interaction of belief and disbelief, both Magecraft and Magic, drawing their power from the same origin, would weaken, and the same thing will happen with all the magi in the world. - Kara no Kyoukai Chapter 5: Paradox Spiral
- ↑ It is the most fundamental rule that a weaker Mystery is erased by a stronger one - Fate/stay night Fate Route
- ↑ A composition that is neither natural nor artificial. Eastern ideology can be profound at times. It can create people like you who has attained Mystery while still being human. - Powered Ciel about Ryougi Shiki in Melty Blood