Aristotle’s 'Metaphysics' defends a number of theses about oneness ['to hen']. For interpreting the 'Metaphysics'’ positive henology, two such theses are especially important: 'to hen' and being ['to on'] are equally general and so intimately connected that there can be no science of the former which isn’t also a science of the latter, and to hen is the foundation ['archē'] of number qua number. Aristotle decisively commits himself to both and. The central goal of this article is to improve our (...) understanding of what the 'Metaphysics'’ endorsement of their conjunction amounts to. To this end we explore three manners of being one which enter into Aristotle’s 'Metaphysics': I call them 'unity, uniqueness', and 'unit-hood'. On the view the article defends, it’s unity that’s at issue in Aristotle’s endorsement of and unit-hood that’s at issue in his endorsement of. The 'Metaphysics'’ positive henology as whole, I suggest, is best interpreted by positing a theory-internal distinction between unity, uniqueness, and unit-hood. (shrink)