The “extreme realists” or Platonists, . . . hold that abstractions exist as real entities or archetypes in another dimension of reality and that the concretes we perceive are merely their imperfect reflections, but the concretes evoke the abstractions in our mind. (According to Plato, they do so by evoking the memory of the archetypes which we had known, before birth, in that other dimension.)

“Foreword to the First Edition”
Introduction to Objectivist Epistemology, 2

The extreme realist (Platonist) and the moderate realist (Aristotelian) schools of thought regard the referents of concepts as intrinsic, i.e., as “universals” inherent in things (either as archetypes or as metaphysical essences), as special existents unrelated to man’s consciousness — to be perceived by man directly, like any other kind of concrete existents, but perceived by some non-sensory or extra-sensory means.

The Platonist school begins by accepting the primacy of consciousness, by reversing the relationship of consciousness to existence, by assuming that reality must conform to the content of consciousness, not the other way around — on the premise that the presence of any notion in man’s mind proves the existence of a corresponding referent in reality.

The content of true reality, according to Plato, is a set of universals or Forms — in effect, a set of disembodied abstractions representing that which is in common among various groups of particulars in this world. Thus for Plato abstractions are supernatural existents. They are nonmaterial entities in another dimension, independent of man’s mind and of any of their material embodiments. The Forms, Plato tells us repeatedly, are what is really real. The particulars they subsume — the concretes that make up this world — are not; they have only a shadowy, dreamlike half-reality.

Momentous conclusions about man are implicit in this metaphysics (and were later made explicit by a long line of Platonists): since individual men are merely particular instances of the universal “man,” they are not ultimately real. What is real about men is only the Form which they share in common and reflect. To common sense, there appear to be many separate, individual men, each independent of the others, each fully real in his own right. To Platonism, this is a deception; all the seemingly individual men are really the same one Form, in various reflections or manifestations. Thus, all men ultimately comprise one unity, and no earthly man is an autonomous entity — just as, if a man were reflected in a multifaceted mirror, the many reflections would not be autonomous entities.

“Leonard Peikoff”
The Ominous Parallels, 27
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