The Six Books of Proclus on the Theology of Plato, Volume 2

For since that which is truly being, is the first of the natures that participate of the divine union, it likewise fills intellect from itself. For intellect is being, as replete with being, and is therefore a divine intelligible. And so far indeed as it is deified it is divine, but as filling intellect, and being participated by it, it is intelligible. Intellect also is being, on account of that which is primarily being. But that which is primarily being itself is separate from intellect; because intellect is posterior to being. But imparticipables subsist prior to things which are participated. Hence being which subsists by itself and is imparticipable, is prior to the being which is conjoined with intellect. For it is intelligible, not as co-arranged with intellect, but as perfecting intellect in an exempt manner, because it imparts being to it, and fills it with truly existing essence.