Jew and Christian alike have honoured Martin Buber. If his views are examined and appraised, it will be found that two tenets received his weightiest emphasis. In his early period it was the mystical feeling and mystical experience. In his later period, it was the application of truth to everyday living, the immersion of routine physical existence in spiritual influence that came to matter most to him, or in short, the non-separation of the Overself from the body. The appeal of both these tenets to the Western mind, starved as it was, and is, of deeper inner experience and fearful of being sucked into monastic flight from the world as the only answer to the question "How shall I fulfil my duty as a spiritual being?" is quite obvious, understandable and natural. But there was a metaphysical error in this second phase, expressed in his claim that the ego persists even in the state of alleged union with God, and therefore in his denial that such a union is really what it purports to be. Albert Schweitzer fell into the same error. The only way to expose such an error is to pass through the tremendous and transforming experience itself; but then its validity will exist only for oneself, not for others, unfortunately. What happens then is that the feeling of a personal separate "I" vanishes during the short period of profound inward absorption when "I" is absent, Overself is present. There is really no ego because the mind is not at work producing thoughts. But when the meditation ends, and the ordinary life is resumed, the "I" necessarily is resumed too. In the case of a philosopher--that is, one who has thoroughly understood the nature of the ego--the relationship with this "I" is no longer complete immersion and identification. It is there, yes, but he is detached from it, a witness of it. His world-experience does not contradict his inner experience, hence the latter fulfils the test of ultimate reality.
-- Notebooks Category 25: World-Mind in Individual Mind > Chapter 2: Enlightenment Which Stays > # 214