Mysticism has always been and is generally understood as a form of the inner path that emphasizes the inner experiences and strives for an inner union with God.
The word mysticism has the same root as the French adjective "muet" and the English "mute", which both go back to the Greek verb "myen", meaning "to close one's eyes and ears", i.e. to withdraw from the outer sensory impressions and turn inwards. Thus the word already gives a hint to the "silent tradition", from which OM C. Parkin comes.
Three forms of mysticism can be distinguished, whose levels of consciousness are hierarchically superior to each other.
The lowest level is nature mysticism, which Ken Wilber also calls the first level of transpersonal consciousness. It is the mystical union with the gross realm, which is the lowest order and corresponds to what is understood in philosophy or theology as pantheism in the broadest sense, namely the equation of God and nature.
Superior to pantheism is deity mysticism, the second stage of transpersonal consciousness, for example the union with God in Christianity or with one of the Hindu deities in the Indian Bhakti tradition. This includes above all the "bridal mysticism", which strives for the union of the soul with God as the true inner lover often seen in vivid visions. This union with subtle manifestations of one's own divinity is usually characterized by intense emotional experience up to ecstasy. The limitedness of this level of consciousness in comparison to non-dual mysticism, the third level of transpersonal, "advaitic" consciousness, shows in the fact that the idea, the representational nature of what the mind believes, what God is, is not completely abandoned and God is experienced as "you", as "counterpart" in whatever form. Teresa of Avila, one of the most important mystics of this stage, often described God in very concrete images as the "Lord" and the "King" and the union with Him as marriage, whereby for her as a nun, as "Bride of Christ", Christ usually stood for God. However, the boundaries between the mystical levels of consciousness are fluid, as each higher level integrates the lower one and transitions to the upper or lower level are possible.
There were and are comparatively very few mystics in Western Christian culture, because mystics have always been potential heretics in the eyes of the Church and were exposed to persecution by the Inquisition, since the God experienced directly in one's own soul rarely corresponded to the Church’s dogmatically defined image of God. This was especially true for the representatives of non-dual mysticism, who knew themselves to be one with God and therefore equal to God, which in the eyes of the Church represented self-exaltation and blasphemy. In fact, however, these highest, completely depersonalized dimensions of consciousness were accessible to only very few people in all cultures. In Western culture, besides Meister Eckhart, the French mystic Marguerite Porète deserves special mention. She was accused of heresy, condemned and burned at the stake. Her only work, The Mirror of Simple Souls, which, although under the spell of the Church, has been handed down anonymously in a roundabout way, shows an astonishing correspondence with Advaitic texts, right down to the metaphors. The book describes the purification path of the soul up to its embedding into divine love followed by its fall from love into nothingness. When it is nothing, there is only God. Then, it says, "I am only what God is in me and nothing else. And also God is just that which He is in me. ... for actually there is nothing but Him."
The "Inner Science" taught by OM C. Parkin can be regarded as the way of gaining knowledge in non-dual mysticism; as the theologian and Zen teacher Peter Lengsfeld writes, "mystical knowledge is a direct looking with the eye of contemplation and basically as objectively verifiable as scientific knowledge. This is also confirmed by Ken Wilber's statement: "Both mysticism and science depend on direct consensual evidence“.
Due to the ecclesiastical interpretation of Christian teaching, there is neither a living mystical tradition of the inner path nor living masters in Western culture. Recognition in the form of canonization is basically only posthumous, canonization of living masters, i.e. the return of Jesus Christ in living form, was and is unthinkable.