They hope to get the credit of minute and exact identification by setting up a plurality of intellectual Essences; but in reality this multiplication lowers the Intellectual Nature to the level of the Sense-Kind: their true course is to seek to reduce number to the least possible in the Supreme, simply referring all things to the Second Hypostasis – which is all that exists as it is Primal Intellect and Reality and is the only thing that is good except only for the first Nature – and to recognize Soul as the third Principle, accounting for the difference among souls merely by diversity of experience and character. Instead of insulting those venerable teachers they should receive their doctrine with the respect due to the older thought and honour all that noble system – an immortal soul, an Intellectual and Intelligible Realm, the Supreme God, the Soul’s need of emancipation from all intercourse with the body, the fact of separation from it, the escape from the world of process to the world of essential-being. These doctrines, all emphatically asserted by Plato, they do well to adopt: where they differ, they are at full liberty to speak their minds, but not to procure assent for their own theories by flaying and flouting the Greeks: where they have a divergent theory to maintain they must establish it by its own merits, declaring their own opinions with courtesy and with philosophical method and stating the controverted opinion fairly; they must point their minds towards the truth and not hunt fame by insult, reviling and seeking in their own persons to replace men honoured by the fine intelligences of ages past. Enneads II,9,6
Now, if they are in possession of Intellect, that realm is a union of both and is Truth. This combined Intellectual realm will be the Primal Intellect: we have only then to examine how this reality, conjoint of Intellectual-Principle and its object, is to be understood, whether as combining self-united identity with yet duality and difference, or what other relation holds between them. Enneads V,5,1
If the knowing principle – and specially primal Intellectual-Principle – is valuable and beautiful, what must be present to those of power to see the Author and Father of Intellect? Anyone thinking slightingly of this principle of Life and Being brings evidence against himself and all his state: of course, distaste for the life that is mingled with death does not touch that Life Authentic. Enneads VI,7,29