All men by nature desire to know. An indication of this is the delight we take in our senses; for even apart from their usefulness they are loved for themselves; and above all others the sense of sight". This is the foundation of human knowledge Aristotle presents us with in Book Alpha of the Metaphysics. The next question which we must naturally ask ourselves is, How? How is it that we can have any knowledge at all? We by our very nature desire to know and we love the senses in themselves but what is the relationship between the two and by what faculty are we able to call anything knowledge once sense perception has occurred?
Aristotle sets up as his faculty for knowledge both the active and the passive intellects. We begin to have knowledge through sense experience. We cannot know without sense experience and it is from sense experience that all knowledge is therefore generated. Knowledge for Aristotle is a knowledge of universals, that is, a knowledge of Essences.
Thought is thus the faculty by which we come to comprehend universals. And since material objects are a composite unity of essence and existence, it naturally follows that we grasp the universal through our encounter with the particular. What follows is a series of events which leads to knowledge. The passive intellect receives the image from the sense data and it is stamped upon the passive intellect from the material impression.
From this stamp the active intellect is to draw out of it and somehow make a universal concept from this particular experience. But there is something more at work here. There is something in the mind (more specifically in the soul) that somehow comprehends and makes universals intelligible. Various theories have been postulated concerning this but we shall concentrate on Aristotle and leave the other philosophies for now. What is at work in man is a divine reason immanent in man's soul. Somehow man is connected to and shares in divine reason.
A distinction must be made here. We are not saying that the human soul's capacity to grasp universals is in some way a maker or shares in the pure act of God, but that without this divine reason at work in the souls of men no understanding of universals could take place at all. The mind works on the material given to it, that is it's potential, and from this material it moves to actuality. An example of this is the man who is without music becoming musical. His potential to be musical always existed in him but it wasn't until he studied the particulars of music that he became a musical man.
Aristotle refers in his Meteorology (1072, b 14) .".. that we can live a life like that of a God, a time of reason being broken down where we become aware of the oneness with the principles, whose knowledge is always actual and always complete". The active intellect does not in any way act strictly on material that was already there but undisclosed, it does act on material given to it in sense experience and illuminated by man's reason and divine reason as well. We share in the reason of God Aristotle believed. The philosopher God is a God of pure act, in other words Thought thinking Thought.
This is the goal of man, to achieve a similar state of being in contemplation and reflection. And it is only through the active intellect that man is able to come to universals. The active intellect acts on the passive intellect the way an artist acts on stone to create an image. The artist impresses the form of a knowable object into the stone and the active intellect impresses a knowable object onto the passive intellect. We must not make the mistake here of understanding the active intellect as a medium between the passive intellect and the object to be known. Knowledge for Aristotle is a direct and not mediated relationship.
The relationship of active to passive intellect is that of illumination shared in divine reason whereby man is able to see the universal in the particular and understand or grasp the idea of universal. This I liken to the statue made by the artist. By sharing in divine reason and the reason in his own soul (which I understand to be an imperfect representation of God's) the artist is able to take a universal image in his soul and craft a particular. This particular statue thus becomes a representation of the universals we can synthesize through sense experience.
Aquinas furthered this theory of the active intellect not as a maker but as an abstraction. This abstraction is taking the impressed species and expressing it through the faculty of the active or agent intellect. The material image is given in sense experience and then expressed as a universal to the mind by the very nature of the active intellect which is abstraction. This abstraction is how for Aquinas that we come to know universals. God's pure act is translated here to fallen man by which he can begin his ascent to a higher existence.
The active intellect in Aristotle is not a reason which creates out of nothing. It works on a material given to it, which it promotes from potentiality into actuality. The "one reason" is analogous to matter because it becomes all things; the other is analogous to the efficient cause because it makes all things. The first statement points to the act of apprehending, the second to that of art. Art makes it's objects by making the material become them. And if the analogy is meant to be an exact one the role of the active intellect must therefore be to make the passive intellect it's object so this apprehension can occur.
What is potentially comes to be actually. This implies that there is something similar to Plato's world of Forms insofar as man is cut off to a pre-existing knowledge and with which we are not in communication. Where Plato called it the re-collection of forgotten forms I believe Aristotle to call it divine reason actuating itself in human reason. Because all men by nature to desire to know, and by knowing we share in the being of God..