Ātman · आत्मन् · the inmost self

The self at the centre — not the personality, not the mind, not the biography, but the bare witnessing that all of those happen to. And the Upanishadic claim is that when you get all the way down to it, it is Brahman: tat tvam asi, that thou art. Not a spark of it, not made by it. It. Hold this door open beside the Buddhist one and you can watch two cousins on the same bench contradict each other flatly. Anattā looks for a self among the aggregates and reports there is none. Ātman looks and reports there is nothing else. The Kabbalah stands between them and refuses both: the soul is real (against Buddhism) and it is not God (against Advaita) — it is a portion of God above, which is a deliberately, permanently uncomfortable middle position, and the whole of Jewish mysticism lives in that discomfort.