Mystical experiences concern union with Ultimate Reality. They are consciously unitive and should not be confused with spiritual experiences more broadly. William James identified four marks that justify calling an experience “mystical,” and his framework has aged remarkably well.
First is ineffability: the experience cannot be adequately expressed in words. Like the taste of tea, it must be directly encountered to be understood.
Second is the noetic quality: the experience carries a sense of insight or revelation. It presents itself as disclosing something true about the nature of reality.
Third is transiency: mystical experiences are temporary. The heightened awareness fades, though its aftereffects may endure.
Fourth is passivity: while one may prepare for such an experience, one cannot produce it at will. It arrives unbidden—often unexpectedly—and is traditionally described as a gift of grace.
A fifth mark, often overlooked, is self-transcendence. The experience breaks—or at least cracks—the shell of the ego, opening the person to a larger Reality. This can be both liberating and destabilizing.
