From the Enneads:

The One, as transcending Intellect, transcends knowing: above all need,
it is above the need of the knowing which pertains solely to the
Secondary Nature. Knowing is a unitary thing, but defined: the first is
One, but undefined: a defined One would not be the One-absolute: the
absolute is prior to the definite.

13. Thus The One is in truth beyond all statement: any affirmation is
of a thing; but the all-transcending, resting above even the most
august divine Mind, possesses alone of all true being, and is not a
thing among things; we can give it no name because that would imply
predication: we can but try to indicate, in our own feeble way,
something concerning it: when in our perplexity we object, “Then it is
without self-perception, without self-consciousness, ignorant of
itself”; we must remember that we have been considering it only in its
opposites.

If we make it knowable, an object of affirmation, we make it a
manifold; and if we allow intellection in it we make it at that point
indigent: supposing that in fact intellection accompanies it,
intellection by it must be superfluous.

Self-intellection — which is the truest — implies the entire
perception of a total self formed from a variety converging into an
integral; but the Transcendent knows neither separation of part nor any
such enquiry; if its intellectual act were directed upon something
outside, then, the Transcendent would be deficient and the intellection
faulty.

The wholly simplex and veritable self-sufficing can be lacking at no
point: self-intellection begins in that principle which, secondarily
self-sufficing, yet needs itself and therefore needs to know itself:
this principle, by its self-presence, achieves its sufficiency in
virtue of its entire content [it is the all]: it becomes thus competent
from the total of its being, in the act of living towards itself and
looking upon itself.