The idea of drawing a line between perceivable or rational truths and
imperceivable or divine truths, is fraught with the burning question as
to the limits of human knowledge, a question which to this day remains
unanswered. In the course of time the limits were extended in favour of
imperfect knowledge (but the character of the unknowable was
problematised and questioned). While Thomas was still convinced of the
possibility of proving the existence of a God by the power of the human
intellect, Duns Scotus removed the problem of the existence of a God and
the immortality of the soul from the domain of science, and made both
propositions a matter of faith. William of Occam, more uncompromising
than Duns Scotus, maintained the absolute impossibility of acquiring
knowledge of supernatural things, and taught--on this point, too,
anticipating Kant--that objective knowledge acquired through the senses
should precede abstract knowledge. The last conclusion of nominalism was
thus arrived at, the existence of universal conceptions, or universals,
supposed to exist outside material things--the curse of the Platonic
inheritance--declared to be impossible, and reality conceded to the
individual only. Roscellinus, the founder of this doctrine, had still
been content to deny the existence of the conception of "deity," leaving
the individual persons, Father, Son and Holy Ghost, as real individuals,
untouched.

We see from the foregoing that the universally derided scholasticism
travelled along the whole line of modern thought: from the "realism" of
Thomas, which leaves the universals as yet unassailed by doubt and
occupying the very heart of knowledge, past the first and, to our view,
very modest doubts of the nominalists, to the agnosticism of Bacon, Duns
and Occam.

With the new position of decided nominalism the foundation was prepared
for the experimental sciences on the one hand, and mysticism on the
other. For the conclusion that things supernatural are a closed book to
us may have two results: on the one hand, the rejection of the
transcendental and the victory of science; on the other, the need to
descend into the profoundest depths of the universe and the soul, and
grasp by intuition what common sense does not see.

The time was ripe and the consummators came: Dante in the south, Eckhart
in the countries north of the Alps. With regard to Dante, I will say one
thing only; he gathered together all the achievements of the n