This essay examines the present state of affairs concerning “one of the great literary manuscripts of our time, the great vellum notebook” that Sotheby’s advertised and sold for the first time in 1985. That sale and a subsequent one in 1990 are related to the contents of the notebook as ascertained from finding aids used by the editors of the Cornell Yeats series, including Chapman, as well as from the examination of extant microfilms of the notebook, the location of the original having been lost. Particularly useful for new and on-going textual-genetic studies in Yeats collections at the National Library of Ireland and elsewhere, part III (“Yeats’s White Vellum Notebook [‘MBY 545’]: An Inventory”) lists all poems, plays, essays, introductions, prefaces, notes, diary entries, and materials for A Vision as they occur by page and folio position within the manuscript notebook, as well as within the Cornell series if, to date, corresponding reproductions and/or transcriptions have appeared there.