The concept of the Septenary Constitution describes two distinct beings in man:
(1) The spiritual (or monadic); and
(2) the physical (or somatic), i.e.—
“The man who thinks and the man who records as much of these thoughts as it is able to assimilate.”
†In Theosophy, the spiritual constitution is termed the “imperishable triad.”
It categorizes man into two distinct conditions or states and further elaborates it up to seven as follows:
(1) the upper (solar) triad or the spiritual being composed of three aspects (“principles”); and
(2) the lower (lunar) quaternary or physical being composed of four aspects (“principles”).
The Key to Theosophy explains, that Platonism also regarded man as composed of two beings; one eternal, formed of the same essence as the Absoluteness and the other mortal and corruptible, i.e., transient. The former, the inner or interior man is inextinguishable from the Agathon. The lowest principle of the classification is the human physical soma and transient self, which is the animal-mammal, along with its passions and desires (instincts). The Platonists regarded the gods as the first principles, and the perishable qualities in man to have been developed by the “minor” gods.
THE SEPTENARY PRINCIPLES REPRESENTED BY THE TRIANGLE AND CUBE
The Key to Theosophy (The Septenary Nature of Man) uses the Sanskrit. In English, the cube is:
THE “LOWER QUATERNARY”
(a) Rupa, or Sthula-Sarira // Physical body // the vehicle of all the other “principles” during life.
(b) Prana // Life, or Vital principle // Necessary only to a, c, d, and the functions of the lower Manas, which embrace all those limited to the (physical) brain.
(c) Linga Sharira // Astral body // The Double, the phantom body.
(d) Kama rupa // The seat of animal desires and passions, and the center of the animal man. It is what separates the mortal man from the immortal entity.
THE UPPER IMPERISHABLE TRIAD
(e) Manas — a dual principle in its functions // Mind, Intelligence: which is the higher human mind, whose light, or radiation links the MONAD, for the lifetime, to the mortal man // The future state and the Karmic destiny of man depend on whether Manas gravitates more downward to Kama rupa, the seat of the animal passions, or upwards to Buddhi, the Spiritual Ego. In the latter case, the higher consciousness of the individual Spiritual aspirations of mind (Manas), assimilating Buddhi, are absorbed by it and form the Ego, which goes into Devachanic bliss.*
(f) Buddhi // The Spiritual Soul // The vehicle of pure universal spirit.
(g) Atma // Spirit // One with the Absolute, as its radiation.
Using Plato, the doctrine is further elaborated:
“Now what does Plato teach? He speaks of the interior man as constituted of two parts — one immutable and always the same, formed of the same substance as Deity, and the other mortal and corruptible. These “two parts” are found in our upper Triad, and the lower Quaternary (vide Table). He explains that when the Soul, psuche, “allies herself to the Nous (divine spirit or substance) (1), she does everything aright and felicitously”; but the case is otherwise when she attaches herself to Anoia, (folly, or the irrational animal Soul). Here, then, we have Manas (or the Soul in general) in its two aspects: when attaching itself to Anoia (our Kama rupa, or the “Animal Soul” in “Esoteric Buddhism,”) it runs towards entire annihilation, as far as the personal Ego is concerned; when allying itself to the Nous (Atma-Buddhi) it merges into the immortal, imperishable Ego, and then its spiritual consciousness of the personal that was, becomes immortal.” (see Key to Theosophy)
Warning however, that:
“…you must beware of the general error into which too many even of our Theosophists fall. Do not imagine that because man is called septenary, then quintuple and a triad, he is a compound of seven, five, or three entities; or, as well expressed by a Theosophical writer, of skins to be peeled off like the skins of an onion. The “principles,” as already said, save the body, the life, and the astral eidolon, all of which disperse at death, are simply aspects and states of consciousness. There is but one real man, enduring through the cycle of life and immortal in essence, if not in form, and this is Manas, the Mind-man or embodied Consciousness.” (Helena P. Blavatsky, The Key to Theosophy: The Greek Teachings)