During the ninth century, a British thinker named John Scotus Erigena applied the via negativa along with Aristotelean logic in order to develop a more carefully systematic description of the nature of reality in the neoplatonic view. Noting the crucial distinction between active (or creative) beings on the one hand and what they produce (the created) on the other, Erigena proposed that all of reality be comprehended under four simple categories:

The only creating uncreated being is god, of which we can know nothing except its role as the central source of all.
Creating created beings are the Platonic forms (including human souls) by whose mediation the divine produces the world.
Ordinary things are uncreating created beings, the distant emanations that constitute the natural world as we perceive it.
Finally, uncreating uncreated must once again be god alone.
Thus, Erigena completes the logically tidy picture with a fourth category of existence that contradicts yet must be identified with the first, emphasizing the view that only mystical consciousness can even try to grasp the nature of god. Each human being is a microcosm in whom analogues of these four fundamental elements combine to produce a dynamic whole whose existence and activity mirror those of the universe.
Few of Erigena's contemporaries appreciated the subtlety and logic of this view, however. Subordinating dialectical reasoning to the presumed dictates of revealed religion at every opportunity, many medieval writers defended and even encouraged the kind of deliberate ignorance that results from an unwillingness to question prevailing opinion. The Socratic spirit nearly disappeared