The letter ‘O’ as a concordance entry presents an unusual methodological challenge: across the depth-psychology corpus, it functions not as a unified concept but as a ubiquitous graphic and syntactic marker whose appearances fall into three distinct registers. First, in several texts — particularly the Grof volumes on LSD research — ‘O’ appears as an artifact of OCR-corrupted typesetting, where complex tables and diagrams have been scanned as undifferentiated character streams, reducing substantive psychological content to uninterpretable letter-fragments. Second, in the philological works of Beekes and Autenrieth, ‘O’ anchors Greek lexical entries (οὐλός, ὄψον, ὄργανον, ὅσιος, and others) whose etymological and semantic analysis touches on concepts relevant to depth psychology: wholeness, the sacred, the instrument, the boundary. Third, in Heidegger’s Being and Time, ‘O’ appears in index entries — ‘O. Being,’ ‘O. distance,’ ‘Objective’ — pointing toward the ontological distinction between objectivity and existential being that underlies much depth-psychological critique of positivism. The entry thus serves as a mirror for the corpus itself: its significance lies not in any single doctrine but in the tension between the symbolic density Greek etymology gives to initial-omicron terms and the extent to which depth psychology has drawn, directly or indirectly, on those semantic fields — wholeness (ὅλος), sanctioned reality (ὅσιος), and instrumental reason (ὄργανον) — in constructing its own vocabulary.