"Nothing is left to you at this moment but to burst out into a loud laugh" From "The Spirit of Zen"
The sephira Tiphereth lies at the heart of the Tree of Life, and like Rome all paths lead to it. Well, not all, but Tiphereth has a path linking it to every sephira with the exception of Malkuth. If the Tree of Life is a map then the sephira titled Tiphereth, Beauty, or Rachamin, Compassion, clearly represents something of central importance. What does it represent? Can you imagine in your mind's eye what it might be? Do you feel anything within you when you contemplate Tiphereth? If asked could you define what it stands for? Well, if you can do any or all of these things you are almost certainly barking up the wrong Tree. As Alan Watts comments :
"The method of Zen is to baffle, excite, puzzle and exhaust the intellect until it is realised that intellection is only thinking about; it will provoke, irritate and again exhaust the emotions until it is realised that emotion is only feeling about, and then it contrives, when the disciple has been brought to an intellectual and emotional impasse, to bridge the gap between second-hand conceptual contact with reality, and first-hand experience."
The sephira Tiphereth presents the student of Kabbalah with a conundrum. Whatever you say it is, it isn't; whatever you imagine it to be it isn't; whatever you feel it might be, it isn't; it is an empty room. There is nothing there. The modes of consciousness appropriate to Hod, Yesod and Netzach respectively are not appropriate to something which is clearly and unambiguously shown on the Tree as being distinct from all three. So what is it? The student is told that the Virtue of Tiphereth is Devotion to the Great Work. What is this "Great Work"? The student is told solemnly that in order to find the answer he or she should obtain the Spiritual Experience of Tiphereth, which is the Knowledge and Conversation of the Holy Guardian Angel. So the student runs off and duely reports (after some work in the library perhaps) that the Great Work is the raising of a human being in every aspect to perfection. Or it is the saving of the planet from industrial pollution. Or it is the retrieval and perpetuation of knowledge, or perhaps it is the spiritual redemption of humanity. The student then burns enough frankincense to pay off the Somalian national debt, records endless conversations with the Holy Guardian Angel in the magical record, and impresses all and sundry with an unbending commitment to the Great Work. This enthusiasm, commitment, personal sacrifice and sense of moral purpose leads to the development of a special kind of person: pious, preaching, judgemental, a humble servant of the highest powers with a blind spot of intolerance. Those who inhabit the vicinity of such moral incandescence may have reason to recall that the Vice of Tiphereth is self-importance and pride.
A student can spend years running around in circles, bringing to the planet the benefits of advanced spiritual consciousness, and this seems to be a necessary exercise. People need to sweat various personal obsessions out of their systems, and the empty room of Tiphereth is an excellent set on which to act out a personal drama. If the devotion to the Work is genuine, and if Tiphereth and the HGA are invoked with passion and determination, then sooner or later the hand of fate lends a hand and the student has the shit knocked out in a big way. An attempt to penetrate the nature of Tiphereth does seem to bring about that state which the Greeks called "hubris", an overweening arrogance, self-importance and pride, until eventually the inevitable happens and one's life comes crashing down around one's ears. The resulting mess varies from person to person; in some people every idea about what is important is turned upside down, while in others an emotional attachment to habits, lifestyle, possessions or relationships turns to dust. The daemon of the false self is dealt a massive blow and sent reeling, and in that moment there is a chance for real change and the dawning of the golden sun of Tiphereth.
This is how I interpret the word "initiation": there is a state of being represented by the sephirah Tiphereth which is absolutely distinct from what most people experience as normal consciousness. Once attained the change is irreversible and permanent; it causes a permanent change in the way life is experienced. When it occurs it is recognised instantly for what it is...as if every cell in one's body shouted simultaneously "So that's all there is to it!" This state has been widely documented in many parts of the world, and Alan Watts' book (referenced below) is as guarded and explicit on the subject as any worthwhile book is likely to be.
The symbolism of Tiphereth is three-fold: a king, a sacrificed god, and a child. This three-fold symbolism corresponds to Tiphereth's place on the extended Tree (to be explained in a later chapter), where it appears as Kether of Assiah, Tiphereth of Yetzirah, and Malkuth of Briah, and to these three aspects correspond the king, the sacrificed god, and the child respectively. One interpretation of this symbolism is as follows: if the kingdom is to be redeemed then the king (who is also the son of God - see below) must be sacrificed, and from this sacrifice comes a rebirth as a child. This is a metaphor of initiation. It is also markedly Christian in symbolism, an aspect many explicitly Christian Kabbalists have not failed to elaborate upon, but it would be a mistake to make too much out of the apparent Christian symbolism. The king, the child and the son are synonyms for Tiphereth in the earliest Kabbalistic documents (e.g. the Zohar), and the introduction of divine kingship and the sacrificed god into modern Kabbalah owes a lot more to the publication of "The Golden Bough"  in 1922 than it does to Christianity.
The theme of death and rebirth is an important element in many esoteric traditions, and provides continuity between modern Kabbalah and the mystery religions and initiations of the Mediterranean basin. The initiatory rituals of the Golden Dawn , an organisation which did much to reawaken interest in Kabbalah, were loosely inspired by the Eleusinian mysteries of Demeter and Persephone - at least to extent that the Temple officers were named after the principal officers of the Eleusinian mysteries. The Golden Dawn Tiphereth initiation was, like most Golden Dawn rituals, a witch's brew of symbolism, but it was strongly based on the mysteries of the crucifixion and the resurrection - at one point the aspirant was actually lashed to a cross - and took place in a symbolic reconstruction of the vault and tomb of Christian Rosenkreutz. The following extract  gives the flavour of the thing:
"Buried with that Light in a mystical death, rising again in a mystical resurrection, cleansed and purified through Him our Master, O Brother of the Cross and the Rose. Like Him, O Adepts of all ages, have ye toiled. Like Him have ye suffered tribulation. Poverty, torture and death have ye passed through. They have been but the purification of the Gold."
Gold is a Tiphereth symbol, being the metal of Shemesh, the Sun, which also corresponds to Tiphereth. Gold is incorruptible and symbolises a state of being which is not "base" or "corrupt"; again, it is a symbol of initiation, of a state of being compared to which normal consciousness is corruptible dross.
I do not wish to go any further into this kind of symbolism - there is an awful lot of it. It is possible to write at great length and succeed in doing nothing more than losing the reader in a web of symbolism so dense and sticky that the inner state one is pointing at becomes a sterile thing of words and symbols. I wanted to provide an idea of how a large amount of exotic symbolism has accreted around Tiphereth, but that is all. The state indicated by Tiphereth is real enough, and lashing comfortably-off middle-class aspirants to a cross in a wooden vault at the local Masonic Hall and prattling on about poverty, torture and death is somewhat wide of the mark.
In the traditional Kabbalah the sephira Tiphereth corresponds to something called Zoar Anpin, the Microprosopus, or Lesser Countenance. As might be expected, there is also something called Arik Anpin, the Macroprosopus, or Greater Countenance, and this is often used as a synonym for the sephira Kether. The symbology connected with the Greater and Lesser Countenances is extremely complex: the "Greater Holy Assembly" , one of the books of the Zohar, is largely a detailed description of the cranium, the eyes, the cheeks, and the hairs in the beard of both the Greater and Lesser Countenances. In a crude sense the Macroprosopus is God, and the Microprosopus is man made in God's image, hence the symbolism, but this is too simple. The Microprosopus is also the archetypal man Adam Kadmon, a mystical concept which should not be confused with a real human being. Adam Kadmon is androgynous, male and female, Adam-and-Eve in a pre-manifest, pre-Fall state of divine perfection. The symbology of the Macroprosopus, Microprosopus, and Adam Kadmon appears to exist independently of the concept of sephirothic emanation, and it is probably fair to say that the former was more highly developed during the Zoharic period of Kabbalah, while the latter is used almost exclusively at the present time - I have yet to encounter a modern Kabbalist with much insight into the thirteen parts of the beard of the Macroprosopus.
Another rich set of symbols associated with Tiphereth comes from the divine name of four letters YHVH, usually written as Jehovah or Yahweh. The letter Yod is associated with the supernal father Chokhmah, and the letter He is associated with the supernal mother Binah. The letter Vov is associated with the son of the mother and father, and is both the Microprosopus and the sephira Tiphereth. The final He is associated with the daughter (and bride of the son), the sephira Malkuth. Tiphereth is thus the "child" of Chokhmah and Binah, and also "the son of God". In Hebrew the letter Vov can represent the number 6, and in Kabbalah this refers to Chesed, Gevurah, Tiphereth, Netzach, Hod and Yesod, the six sephiroth which correspond to states of human consciousness and hence also to the Microprosopus. With a typical Kabbalistic flexibility they can also stand for the six days of Creation.
The illusion of Tiphereth is Identification. When a person is asked "what are you", they will usually begin with statements like "I am a human being", "I am a lorry driver", "I am Fred Bloggs", "I am five foot eleven". If pressed further a person might begin to enumerate personal qualities and behaviours: "I am trustworthy", "I lose my temper a lot", "I am afraid of heights", "I love chessecake", "I hate dogs". It is extremely common for people to identify what they are with the totality of their beliefs and behaviours, and they will defend the sanctity of these beliefs and behaviours, often to the death - a person might have behaviours which make their life a misery and still cling to them with a grip like a python. This inability to stand back and see behaviour or beliefs in an impersonal way produces a peculiar ego-centricity: the sense of personal identity is founded on a set of beliefs and behaviours which are largely unconscious (that is, a person may be unaware of being grotesquely selfish, or pompous, or attention-getting) and at the same time seem to be uniquely special and sacred. When behaviour and beliefs are unconscious and incorporated into a sense of identity it becomes impossible to make sense of other people. If I am unaware that I regularly slip little put-downs into my conversation, and Joe takes umbrage at my sense of humour, then rather than change my behaviour (which is unconscious) I interpret the result as "Joe doesn't have a sense of humour; he needs to learn to laugh a little". There are many behaviours which may seem innocuous to the person concerned but which are irritating or offensive to others, and when the injured party reacts appropriately it is impossible for me to make sense of this reaction if my behaviour is unconscious and tightly bound to my sense of identity. Our sense of identity thus becomes a kind of "Absolute" against which everything is compared, and judgements about the world become absolute and almost impossible to change, even when we realise intellectually the subjectivity of our position. Referring to this projection of the unconscious onto the world Jung  comments:
"The effect of projection is to isolate the subject from his environment, since instead of a real relation to it there is now only an illusory one. Projections change the world into one's unknown face."
In summary, the illusion of Tiphereth is a false identification with a set of beliefs or behaviours. It can also be an identification with a social mask or Persona, something discussed in the section on Netzach. So to return to the orginal question: "what are you?". Is there an answer? If the answer is to be something which is not an arbitrary collection of emphemera then you are not your behaviours - behaviour can be changed; you are not your beliefs - beliefs can be changed; you are not your role in society - your role in society can change; you are not your body - your body is continually changing. Out of this comes a sense of emptiness, of hollowness. The intellect attempts to solve the koan of koans but has no anchor to hold on to. Is there no centre to my being, nothing which is me, no axis in the universe, no morality, no good, no evil? Do I live in a meaningless, arbitrary universe where any belief is as good as any other, where any behaviour is acceptable so long as I can get away with it? This sense of emptiness or hollowness is the Qlippoth or shell of Tiphereth, Tiphereth as the Empty Room with Nothing In It. Jung  provides a memorable and moving description of how his father, a country parson, was progressively consumed by this feeling of hollowness. There can be few fates worse than to devote a life to the outward forms of religion without ever feeling one touch of that which gives it meaning.
The God Name of Tiphereth is Jehovah Aloah va Daath, or simply Aloah va Daath. It is often translated as "God made manifest in the sphere of the mind". The Archangel is sometimes given as Raphael, but I prefer the attribution to Michael, long associated with solar fire. His name "Who is like God" reinforces the upper/lower relationship between Kether and Tiphereth. The angel order is the Malachim, or Kings.
To cover all of the traditional material related to Tiphereth is to cover most of Kabbalah. Tiphereth is at the centre of a complex of six sephiroth which represent a human being. This isn't a modern interpretation, an "initiated" interpretation of obscure medieval documents. Kabbalah has always been deeply concerned with the dynamics of the relationship between God and the Creation, between God and a human being, and the descriptions of the Macroprosopus and Microprosopus in the Zohar are a bold attempt to grasp something ineffable using a language built from the most immediate of metaphors, the human body. According to the Bible and Kabbalah, a human being is in some sense a reflection of God, and to the extent that Kabbalah is an outcome of genuine mystical experience it is a description of the dynamics of that relationship, and more importantly it is a description of something real. Even if you don't like the look of the word "God" (I don't) Kabbalah is trying to express something important about a relatively inaccessible dimension of human experience. Tiphereth is a reflection of Kether and represents the "image of God", the "God within", whatever you take that to mean; it is a symbol of centrality, balance, and above all, wholeness. It can be an empty room, a gaping emptiness, or it can be the heart and blazing sun of the Tree. It is the symbol of a human being who lives in full consciousness of the outer and the inner, who denies neither the reality of the world nor the mystery of self-consciousness, and who attempts to reconcile the needs of both in a harmonious balance.