[Footnote 1:  R. Zimmermann, Nikolaus Cusanus als Vorlaeufer Leibnizens, in vol. viii. of the Sitzungsberichte der philosophisch-historischen Klasse der Akademie der Wissenschaften, Vienna, 1852, p. 306 seq.  R. Falckenberg, Grundzuege der Philosophie des Nikolaus Cusanus mit besonderer Beruecksichtigung der Lehre vom Erkennen, Breslau, 1880.  R. Eucken, Beitraege zur Geschichte der neueren Philosophie, Heidelberg, 1886, p. 6 seq.; Joh.  Uebinger, Die Gotteslehre des Nikolaus Cusanus, Muenster, 1888.  Scharpff, Des Nikolaus von Cusa wichtigste Schriften in deutscher Uebersetzung, Freiburg i.  Br., 1862.]

Human knowledge and the relation of God to the world are the two poles of the Cusan’s system.  He distinguishes four stages of knowledge.  Lowest of all stands sense (together with imagination), which yields only confused images; next above, the understanding (ratio), whose functions comprise analysis, the positing of time and space, numerical operations, and denomination, and which keeps the opposites distinct under the law of contradiction; third, the speculative reason (intellectus), which finds the opposites reconcilable; and highest of all the mystical, supra-rational intuition (visio sine comprehensione, intuitio, unio, filiatio), for which the opposites coincide in the infinite unity.  The intuitive culmination of knowledge, in which the soul is united with God,—­since here even the antithesis of subject and object disappears,—­is but seldom attained; and it is difficult to keep out the disturbing symbols and images of sense, which mingle themselves in the intuition.  But it is just this insight into the incomprehensibility of the infinite which gives us a true knowledge of God; this is the meaning of the “learned ignorance,” the docta ignorantia.  The distinctions between these several stages of cognition are not, however, to be understood in any rigid sense, for each higher function comprehends the lower, and is active therein.  The understanding can discriminate only when it is furnished by sensation with images of that which is to be discriminated, the reason can combine only when the understanding has supplied the results of analysis as material for combination; while, on the other hand, it is the understanding which is present in sense as consciousness, and the reason whose unity guides the understanding in its work of separation.  Thus the several modes of cognition do not stand for independent fundamental faculties, but for connected modifications of one fundamental power which work together and mutually imply one another.  The position that an intellectual function of attention and discrimination is active in sensuous perception, is a view entirely foreign to mediaeval modes of thought; for the Scholastics were accustomed to make sharp divisions between the cognitive faculties, on the principle that particulars are felt through sense and universals thought through the understanding.  The idea on which Nicolas bases his argument for immortality has also an entirely modern sound:  viz., that space and time are products of the understanding, and, therefore, can have no power over the spirit which produces them; for the author is higher and mightier than the product.