Full Idea
Intellectual-Principle [Nous] by its intellective act establishes Being.
Gist of Idea
Being is the product of pure intellect
Source
Plotinus (The Enneads [c.245], 5.1.04)
Book Reference
Plotinus: 'The Enneads', ed/tr. Mackenna,Stephen [Penguin 1991], p.351
A Reaction
This is a surprising view - that there is something which is prior to Being - but I take it to be Plotinus giving primacy to Plato's Form of the Good (a pure ideal), ahead of the One of Parmenides (which is Being).