Page "Proclus" Paragraph 17

The principle which is produced below the level of the One and the Henads is the divine Intellect ( Nous ).

The One cannot have a determinate nature if it is to be the source of all determinate natures, so what it produces is the totality of all determinate natures, or Being.

By determination is meant existence within boundaries, a being this and not that.

The most important determinate natures are the Greatest Kinds from Plato's Sophist ( Being, Same, Other, Rest, Motion ) and Aristotle's ten categories ( Quantity, Quality, etc .).

In other words, the One produces what Plato called the Forms, and the Forms are understood to be the first determinations into which all things fall.

The One produces the Forms through the activity of thinking.

The One itself does not think, but instead produces a divine mind, Intellect, whose thoughts are themselves the Forms.

Intellect is both Thinking and Being.

It is a mind which has its own contents as its object.

All things relate to the first principle as both One and Good.

As Being, Intellect is the product of the One.

But it also seeks to return to its cause, and so in Thinking it attempts to grasp the One as its Good.

But because the simplicity of the One / Good does not allow Intellect to grasp it, what Intellect does is generate a succession of perspectives around its simple source.

Each of these perspectives is itself a Form, and is how Intellect generates for itself its own content.