Human being is tripartite in nature, but it is just an illusion of our language, a convenience of Western thought and communication that has evolved in the Western psyche, having become archetypal. When we discuss our nature, the Western tendency is to dissect and analyze our subject, so we speak of the tripartite nature of humans. In all reality, Body, Soul, and Spirit are actually one.
Man has no Body distinct from his Soul for that call'd Body is a portion of Soul discern'd by the five Senses, the chief inlets of Soul in this age (William Blake, The Marriage of Heaven and Hell).
Har and Heva bathing, Mnetha looking on, by William Blake
In the passage above, Blake prefers to discuss only Body and Soul, but stresses that they are indistinct. He calls Body "a portion of Soul discerned by the five senses." Perhaps he does not discuss Spirit because of the overemphasis that has been placed on Spirit in the West for many centuries. Western culture is primarily a Spirit-seeking society, even though many would deny this. We have been obsessed with Spirit for a long, long time. Spirit is ubiquitous in our culture. It is the driving force behind many Western standbys, like capitalism, technology, industry, religion, and even some mysticism and new age teachings. Anytime you hear someone talking about transcendence, you can bet Spirit is close by. Spirit is overemphasized at the expense of Soul. Many have forgotten about Soul, since it is much messier and less glamorous. We would rather soar in the heavens than slog through the morasses and quagmires of Soul. I believe Blake recognized what the overemphasis of Spirit had done to his world.
Spirit, however, is also a portion of Soul. Soul is actually the Mediatrix, the in-between of Spirit and Body. Speaking of Neoplatonism, James Hillman writes,
This tradition holds to the notion of soul as a first principle, placing this soul as a tertium between the perspectives of body (matter, nature, empirics) and of mind (spirit, logic, idea). Soul as tertium, the perspective between others and from which others may be viewed, has been described as Hermetic consciousness (Lopez-Pedraza 1977), as "esse in anima" (Jung , CW 6, §66, §77), as the position of the mundus imaginalis by Corbin, and by Neoplatonic writers on the intermediaries or figures of the metaxy (Archetypal Psychology, p. 5).Western thinking has been primarily focused on Body and Spirit alone, matter and mind in the Cartesian manner. This sort of dualism goes back much further, to perhaps the 9th century, at the Eighth General Council of Constantinople. In Canon 11, the council ruled that,
...the Old and New Testaments teach that man has one rational and intellectual soul, and this is the teaching also of all the fathers and doctors of the Church... (Medieval Sourcebook:Basically, the Church said that only the rational mind is the Soul, but it is really an element of Spirit, thus leaving human being with only Body and Spirit. This is a gross misunderstanding. The rational mind originates with Spirit. Spirit has been the driving force behind Western progress ever since. The constant need for ascent and transcendence is the classic archetypal motif of Spirit. Spirit soars into the very upper regions of the atmosphere. It is most at home in very high places, where the air is thin and light, where one can sit atop and apart from the world and be superior to it. Spirit is cold, since the higher one ascends, the lower the temperature and the thinner the air. There is a snowy whiteness about spirit that makes it chilly and vapid, if taken to extremes. When you hear someone refer to "spiritual detachment," you'll know that the archetype of spirit is present.
Eighth Ecumenical Council: Constantinople IV 869-70).
Spirit is a valid, necessary human experience. A problem arises, however, when it is pursued to the exclusion of Soul. Spirit is height, but Soul is depth. What would we be like without depth? We would be cold, inanimate automatons, going around making positive affirmations, bathing in the light and rejecting the darkness. Spirit seeks intelligence, while Soul seeks imagination. We need both, of course, but we must never overemphasize one over the other. So many problems in our world have been caused by just this.
Even though there are three valid archetypal images of the human makeup, when all is said and done, all three are one, as are all things in our universe. All is animaterial, the intermingling of Body, Soul, and Spirit into one animaterial whole. Three in One, in all things, according to their various modes of presence. Humans have one mode of presence; animals another; and even stones have their mode of presence. In all things, however, human and otherwise, Soul is the tertium.