A common theme in the esoteric philosophies of the Middle East (Gnosticism, Manichaeism, Ishraqism, Sufism, etc) is that of the Heavenly Twin, the Angelic Spirit, the Guide of Light. This theme of the Guide ties in with the idea of the "guardian daimon (angel)" of the Platonic tradition. As Henry Corbin explains:
"...Plotinus (Enneads 3:iv) speaks of the daimon paedros into whose care we are given, and who is the guide of the soul throughout life and beyond death....Apuleius (De Deo Socratis, 16) (deals) with the higher group of daimons to each of whom the care of one human individual is entrusted and who serves as its witness and guardian...Philo of Alexandria calls the Nous (Divine Intellect) the true man, the man within man...who dwells in the soul of each of us, now as archon (ruler) and king, now of judge...on occasion he plays the part of a witness, sometimes even of a prosecutor..."
[Henry Corbin, The Man of Light in Iranian Sufism, pp.34-35]
What is being referred to here is not an impersonal or transpersonal principle, like the Vedantic Atman or Buddhist Shunyata (Emptiness) or Dharmata (Reality), but rather the Divine Soul or Higher Self. Which is not to deny the impersonal Absolute but simply to say taht this exists as well. This is a principle that is not so much impersonal but super-personal. It is the True personality, the god within, the indwelling Divine Presence. As a Personality, it is both a Guide and a "Heavenly Twin".
It could be said that the Higher Self constitutes a definite Personality quite distinct from the everyday personality and ego. The distinction between these two personalities is important, for here we have the fundamental polarity of the human being (and for that matter, of any evolving being).
On the one hand, there is the everyday personality, derived from the physical body and from the various psychic principles. It is this which constitutes the ego; what we mean when we say "I", and indeed the faculty that does say "I"; the imperfect worldly being.
On the other hand, there is the Higher Self, the Divine principle, immortal and perfect yet paradoxically still evolving; the Spiritual Guide, the "inner voice", the Divine Presence, the true soul.
And finally the transcendent Higher Self, the being of Light; immortal and eternal, the true self.
note: The following material on the Higher Self is from an email by Arvan Harvat (Thu, 23 Dec 1999) (my hyperlinks added).
Right now, I'm chewing some Sufi stuff ( Ibn Arabi, Kubra, Nasafi,.) on Higher Self. Interesting. Succinctly: looks like it's a, so to speak, Mediterranean tradition ( Greece/Neoplatonism, Iran, Sufism, Kabbalah, Egypt ( ? ),..) of "Man of Light", Heavenly Person who is both "above" & within a heart. Moody's "Being of Light" or Jung's psychogogue or Valentinian's Angel- very anthropomorphic, ( Heavenly Guide, Guardian Angel, daimon, Celestial Twin, Evanescent Youth, Fravashi, Nous, ..), who:
In short - a very, very anthropomorphic & operating Higher Self, Great Person who is you ( your Higher Self is not mine, although at the root...).
In Assagiolian parlance: Transpersonal Self is like a wave in the ocean of the Universal Self; or like a sun in the galaxy with great central Sun ).
You ( and I and everyone ) have, this moment, right now, inside or above ( topologically irrelevant ) a (Trans)personal Guide, Watcher who eagerly ( and patiently ) waits for your call or pledge ( not only "spiritual" ). As a Sufi saying goes "You make a one step towards me - I'll make ten towards you".