To understand the relevance of the archetypes to Neoplatonism, we can begin by observing that an archetype is incompletely manifested in any particular concrete situation, which leads to it being recognized as existing independently as a field of structured potentiality.  Thus an archetype is an independent, universal form guiding perception and behavior.

Since many of the human instincts govern our relations with other humans, the most familiar archetypes are personified.  Indeed, as Jung stresses, the archetypes behave as autonomous personalities, independent of our conscious control.  This is because consciousness is just one part of the total psyche; like an organ, it has evolved because of the selective advantage it confers on our species.  It therefore functions as one element in the panoply of our psychological faculties.  As a consequence of their numinous autonomy, the personified archetypes are experienced as gods, and the relations among them provide the basic structure of mythology.

However, it is a mistake to think the archetypes are “merely psychological,” with the implication that they are in some way imaginary and subjective. Rather, they are objectively real in that they are empirical, stable, and public.  They are empirical in that their existence and character can be inferred from their effects in experience; they are stable in that they are (relatively) unchanging; and they are public in that they are common to all humans.  (Thus Jung calls the collective unconscious the objective psyche.)  Therefore, the archetypes exist, but not in a physical way; they are immaterial forms governing the dynamics of perception and behavior.  In this sense the archetypes are as real as the human genome, the laws of nature, and the laws of mathematics.

The archetypes are a source of transcendent meaning because they integrate individual lives into the greater patterns of humanity and the universe; the archetypes give transpersonal meaning and significance to situations and relationships in human life.  Archetypally meaningful situations or relationships are numinous (that is, hallowed, miraculous, uncanny, supernatural, or the like); being in love is a familiar example (Stevens 1982, 67–8, 199), a θεῖα μανία (divine madness).

Hitherto I have stressed the grounding of the archetypal Ideas in human genetics.  However, it is essential to recognize, as did Jung (CW 8, ¶420), that any physical process that has a psychical aspect and is common to all people is, by definition, archetypal (Stevens 1982, 71).  This is because the archetypes are the components of the objective psyche and, as we have seen, to be objectively real, they must be public, stable, and empirical (that is, have conscious effects even though, as causes, they are unconscious).  Therefore any natural law will be archetypal, provided that it also has a psycho-spiritual aspect, that is, provided that it conditions perception, behavior, and meaningful experience.  As Marie-Louise von Franz (1974, 7) says, “The lowest collective level of our psyche is simply pure nature.”

Human instincts mostly mediate interrelations among humans, therefore most of the archetypes are personified (that is, experienced as personalities: the gods).  In contrast, the non-human-specific archetypes are not usually personified, and so they are experienced more as impersonal forces, but with a psychical aspect.  For example, all animals make distinctions, and the experiences of discriminating one thing from another, and of settling into a course of action, are archetypal experiences, which are correlated to fundamental neural processes.  Therefore dichotomy and decision may have a numinous quality.

The laws of nature obey the laws of mathematics, and like a true Pythagorean, Jung thought that the most fundamental archetypes are numerical; we may call them the archetypal numbers.  In a letter he wrote, “I have a distinct feeling that number is a key to the mystery, since it is just as much discovered as invented.  It is quantity as well as meaning” (von Franz 1974, 9).  Von Franz (1974) has made an important start on unraveling the archetypal structure of the numbers.

For example, as we’ve seen, duality (that is, the Dyad) is the archetypal Idea underlying experiences of dichotomy, opposition, or clear differentiation.  Psychologically, it is the archetypal experience of a neural system settling into one of two dynamical “attractors.”  Conjunction (that is, the active Triad) leads to the experience of the resolution of a state of conflict, the bridging of a gap, or relaxation into a stable state.  The passive Triad, in contrast, underlies the experience of the mean, that is, of balance between two opposed extremes.  The Tetrad is the foundation of experiences of completeness and equilibrium, as shown in Jung’s extensive studies of the quaternio.  The Monad, of course, underlies our experience of identity, as when we recognize something, grasping what it is, or its being.  The most profound experience of unity arises when, under conditions of mental quiet, the brain ceases its construction of a model of the body and its surroundings, the fundamental duality of self and other.  When the illusion of duality is dropped, we experience unity.

Finally, the Monad and Indefinite Dyad, as a pair, underlie our experiences of sameness and difference; recall Plato’s Circles of the Same and the Different in the World Soul.  Similarly, Φιλότης and Νεῖκος, “Love” and “Strife” (so called), are fundamental forces at many levels of reality: unity and division; cooperation and competition in evolution, and the cooperative-competitive dynamics of many natural systems, which leads to self-organization.