True samadhi is not restricted to peaceful and pleasant moments of deep concentration but, rather, is all moments and all reality, each truly precious, not only the calm and pleasing. Soto ancestors have criticized limited views of samadhi as only peaceful and pleasant states, only times of deep concentration, only experiences to be entered into then departed from, only certain conditions that emerge and are attained, only a matter of body and mind. True samadhi exists always, is not dependent on whether peace or bliss is experienced or not experienced, cannot be attained or lost, never emerges or departs.
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Samghānandi ... was sitting peacefully, entered into samadhi. The Venerable [Rahulabhadra] and his congregation waited for him. When three seven-day periods had passed, [Samghānandi gradually] arose from his samadhi. The Venerable [Rahulabhadra] asked, “Is your body in samadhi or is your mind in samadhi?” [Samghānandi] said, “Body and mind together are in samadhi.” The Venerable [Rahulabhadra then] said, “If body and mind together are in samadhi, then how can there be emerging from it or entering into it?”
Rahulabhadra means that, if body and mind are in the true samadhi of all reality (as we always are), there is no body nor mind, no in vs. out, and thus true samadhi is not some state to enter or exit.
... The meaning of this somewhat puzzling exchange becomes a clearer if we recall that, in Zen Wisdom, one does not truly come and go from reality even as we come and go in life, there is no “entrance” nor “exit” from wholeness even as we may enter and exit concentration or any other states, there are no “starts” or “finishes” in the timeless-unbroken even as time has starts and finishes, nor does the whole (being so whole) have an “inside” as opposed to an “outside,” nor separate somethings called “body” and “mind,” even as we experience so in practical terms. The wholeness of reality is all of this, all true at once, thus true samadhi sweeps in all these seemingly incongruous views.