Without true Jhana , the Imageless reality of Zen remains a lifeless mystery. Because it is lifeless to any worldling devoting its mind to follow images of a myriad shapes and functions, it carries no attraction to them since they refuse consciously or subconsciously be Mind-full (of its nature).
What has no [force/light of] life, is empty of Truth, and what is empty of truth brings inevitably misery and suffering to the mind. Spirit  defiled, means birth and death, while Spirit that is pure, means enlightenment and deathlessness.
What stands face to face with the imageless reality of Zen knows the living mystery of the Imageless Mind. To such a great being this Mind permeates the all, not as the all, but as purely ITSELF. For where the worldling is bewitched by the wave-forms, that never ends to change form, the student of the way knows the pure, unborn Essence of the One Mind is behind them all.
Original self-nature is the Mind; the Mind of your true self is the very self-nature all Buddhas and Mind Masters have spoken about at great length. This Buddha’s mind, the former Buddha and later Buddha, are all transmitting the same mind. Beyond this Imageless Mind, of no birth and no death, there is only instantenuous becoming, of any-thing, be it a breath, a thought, a memory, a feeling or even a doubt.
The path into the heart of this Mind, is one of a onepointedness. To most this path is dead and filled with darkness, but to a few it is filled with a great bright light, the closer they approach the other shore.
Whether you raise a Katana, make a swift motion with a brush over a white sheet of paper, take a singel breath, or step, whether you produce a single thought, or instant fear, or doubt; behind all these phenomena, IT is instantly there serving the desiring Self as its great Imageless Master.
It is flawless; perfectly dynamic, proven instantly by any of its born positions originating simultaneously from its originally supra-positional state, and as such it stands as the Alpha and Omega behind all things. Not a god, not a thing, but Mind Only.
It is this Mind all Mind Masters have come to know directly and unequivocally as the One Mind, the Unborn Mind, the First Principle, the Uncreated, and so on.
A Mind Student of good merit, possessed with a sharp faculty, a strong Spirit, one of no major divisions, not easily distracted, able to focus his mind on THAT which precedes any given action or phenomenon at any given moment, is considered one able to cross over Hakuins life-taking log bridge, to the other shore of deathlessness and nirvana.
Let your one-pointed practise begin with a single step and discover instantly with this single step, or motion of your Mind´s sharp blade, that fears nothing in the realms of birth and death, the True Body-of-the-Sage.
 Etymology; From Sanskrit ध्यान – dhyāna, Ancient Chinese 禪 ɖjen, Mandarin 禅 Chán which is an abbreviation of 禪那 (ɖjenna), evolving into Japanese 禅 zen
 Spirit= Pure Will – Life force .