“Standing before all things, there must exist a Simplex, differing from all its sequel, self-gathered not interblended with the forms that arise from it, and yet in some mode of its own to be present to those others: it must be authentically a unity, not merely something elaborated into a unity and so in reality no more that unity’s counterfeit; it will debar all telling and knowing except that it may be described as transcending Being – for if there were nothing outside all alliance and compromise, nothing authentically one, there would be no Source. Untouched by multiplicity, it will be wholly self-sufficing, and absolute First, whereas any not-first demands its earlier, and any non-simplex needs the simplicities within itself as the very foundation of its composite existence.”
Plotinus, Enneads, V. 4, How the Secondaries Rise from the First: And on the One, 1.
“That awesome Prior, The Unity, is not a being, for so its unity would be vested in something else: strictly no name is apt to it, but since name it we must there is a certain rough fitness in designating it as unity with the understanding that it is not the unity of some other thing.
… Think of The One as Mind or as God, you think of it too meanly; use all the resources of understanding to conceive this Unity and, again, it is more authentically one than God, even though you reach for God’s unity beyond the unity the most perfect you can conceive. For This is utterly self-existent, with no concomitant whatever. The self-sufficing is the essence of its unity. Something there must be supremely adequate, autonomous, all-transcending, most utterly without need.
Plotinus, Enneads, VI. 9. On the Good, or the One, 5-6.