I would assume that "projection" here is equivalent to the concept of "manifestation" or "emanation".
I'm not well-enough informed about Buddhist philosophy to address the topic of "emanation" with much certainty. From the two sources below, "The Ontodynamics of Emanation: An Exercise in Speculative Metaphysical" (by M. Alan Kazlev) and the Wikipedia entry for "Emanationism," an emanation is: a particular, specific, finite form of what is called the "Absolute" in philosophy - whether Eastern or Western, religious or nonreligious philosophy.
I'm most familiar with the early nineteenth century German "Idealist" philosopher, Georg Hegel's idea of the Absolute. As I understand it, "change" ("becoming") is viewed as the Absolute (since nothing is permanent.)
The Absolute is a form of "being" that can't be "contradicted" by an opposite idea. When philosophy talks about "being," it is talking about existence in its broadest possible sense. Philosophy uses the word "being" as a starting point in its taxonomy of all existence, much as a botanist might divide the plant "kingdom" into a taxonomic universe of particular species of plants, as the Swedish botanist, Carl von Linné (Carl Linnaeus), divided the plant Kingdom into 25 classes in 1754.
"Being," therefore, is the most general term possible that includes anything and everything which has an "existence." (It may also includes anything and everything that once existed but no longer exists, or has the potential for existence, or even once had the potential for existence.)
But this generalization of "being" makes no distinction between separate forms of being - into which everything in the universe might be divided into, as specific instances of "being" (on all possible planes of existence). This general, Absolute form of "being" remains undifferentiated, non-specific, amorphous. It is a broad, bland, homogeneous form "being" that turns all being into an intellectual monolith: an unbroken "totality" of being.
Any sort of differentiation between one thing and another gives each of them a "separate" form of "being." Thus, going back to Carl Linnaeus, the eighteenth century Swedish botanist, for example, the separation of groups of plants into a "taxonomy" of different species gives each of those species a separate identity (a separate form of "being," in other words). Further distinction between things are always possible, perhaps infinitely so. Once Carl Linnaeus divided the plant kingdom into different species, these species could be further divided within themselves into the individual plants (specimens) that belong to a particular group of plants botany has classified together as a "species."
Jean-Paul Sartre, the mid-twentieth century French Existentialist philosopher points out that "being" is contradicted by "non-being" ("nothingness," in other words). Since there is always a possibility of negation of "being" - since it can always be contradicted by "non-being" (nothingness) - he is led to question whether there can be an Absolute form of "being."
"Manifestation" is the particular form that finite forms of being take in the world. Again, using botany as an example, the "manifestations" of the plant kingdom would be individual specimens of any particular species of plant. (But I'm not precisely certain how Buddhism uses the term, "manifestation," though. I think it might be applied to both: 1. any of the specific forms that a more general principle "manifests" itself in and 2. the specific forms our "Buddhist nature" shows - or "manifests" - itself within us.)
The Ontodynamics of Emanation: An Exercise in Speculative Metaphysical(text content by M.Alan Kazlev)
http://www.kheper.net/topics/emanation/emanation.htmlBefore defining the laws of emanation, a basic proviso needs to be stated. And that is that emanation does not pertain to the Absolute Reality....all of the stages of manifestation of the Supreme are complementary or non-contridictory with each other. Nor can there actually be a coming into (or a passing out of) being, because all aspects of the Absolute are eternal in any case, and at the level of the Absolute there is nothing else but the Absolute, so there is nothing for the Emanator to emanate into. Emanation can only occur within the realm of duality itself.
How then does one get from unity and plenum of Being, as represented by the Absolute or Supreme Godhead/Reality, to the duality of Being and Non-being, and the fact of separate existence, as representative of ordinary (and not only ordinary, but also psychic, spiritual, and even higher) reality?
The answer - and on this point our various sources seem to be in full agreement - is that the Absolute Reality, the Absolute or Supreme Godhead, forms within Itself (all this is speaking metaphorically of course; remember that, ultimately, there is nothing else but the Absolute) a duality, a set of polar opposites. In this way the One becomes Two, and there is "room" for emanation.
Hence we have the division of the Tao or Tai Chi into Yin and Yang, the division of Paramashiva or Parasamvit into Shiva and Shakti, the division of The One into the Finite and the Infinite, the division of the Light of the En Sof into Hesed and Gevurah...., no matter how many examples are given, they all present the same basic principle, although often approached in different ways and from different perspectives. For example, the Tantric Shakti is by no means the same as the Taoist Yin (although both are identified with the female principle). But both Tantricism and Taoism agree that the One becomes Two, and that this is the beginning of creation...
It is at this same level that the process of emanation occurs. The pure Monistic teaching (for example Advaita Vedanta or Prajnaparamita Buddhism) is beyond emanation, but if the origin and nature of the cosmos and finite existence is to be taken into account (which most of these Monists are not interested in doing, because of their single-minded dedication to Liberation) then the theory of emanation has to be considered.
My own understanding of the original Polarisation of the Absolute - the One becoming Two - is that it is the polarisation of the Absolute or Supreme into the Absolute Itself, and the self-veiling of the Absolute. In other words, into infinite Being and infinite Non-being, or Light and Dark, Spirit and Matter, Abundance and Lack, Self and Not-self.
So we have the two polarities, the two aspects, each infinite. On the one hand, the Supreme revealing Itself as Itself; as infinite Consciousness, Light, Love, Power, Bliss, Divinity, Perfection, Creativity, etc; the pole of Absolute Spirit. On the other hand, the Supreme veiling or conceiling Itself; as infinite non-consciousness, deprivation, formlessness, receptivity, and non-being; what Plotinus would have called hyle. The Supreme in Its own transcendent nature is of course beyond, but also includes, both these poles, in total unity and harmony.
From the polarity of the Supreme revealing Itself as Itself, the Supreme emanates or radiates out as infinite plenitude all the gods, worlds, beings, and evolutions, into the Supreme veiling Itself as non-consciousness or hyle.
That radiation out from the positive to the negative pole of the Absolute constitutes the process of emanation, and it follows specific laws. These laws have been elaborated in a number of different occult and philosophical teachings: Neoplatonism, Kabbalah, Theosophy, and elsewhere. In the rest of this chapter I will present a brief and unavoidably incomplete definition of these laws of creation. Incomplete, because it would require a weighty volume, and many many philosophical statements and definitions, to do justice to this subject. The Neoplatonist Proclus for example wrote a large book, The Elements of Theology, which thankfully has survived to the present day, in which he attempts a comprehensive definition of the laws of Emanation. But even that work, invaluable as it is, is not complete, because it is only written from a specifically Neoplatonic perspective, and hence does not cover the other equally valid perspectives of different esoteric teachings on this subject.
Wikipedia: Emanationismhttp://en.wikipedia.org/wiki/EmanationEmanationism is Platonic monism, and an idea in the cosmology or cosmogony of certain religious or philosophical systems. Emanation from the Latin 'emanare' meaning "to flow from", is the mode by which all things are derived from the First Reality, or Principle. All things are derived from the first reality or perfect god by steps of degradation to lesser degrees of the first reality or god, and at every step the emanating beings are less pure, less perfect, less divine. Emanationism is a transcendent principle from which everything is derived, and is opposed to both Creationism (wherein the universe is created by a sentient God who is separate from creation) and evolutionism/materialism (which posits no underlying subjective and/or ontological nature behind phenomena, being immanent).
Key Principles
That complex things are created in nature is not in question...Rather, the two principles that are in question are the locus for creation and whether a sentient, self-aware Absolute (‘God’) is a necessity for creation. Emanationists such as Pythagoras, Plotinus, Gotama, and others argued that complex patterns in nature were a natural consequence of procession from the One (Hen, Absolute).
According to Emanationism, the Absolute, its nature and its activity must be inseparably one thing only, namely will, such that the nature and activity of the Absolute is both one and the same (again, will) and by its very nature is also its activity ‘to will’ and wills things to be or occur, thereby maintaining the center of the logical system of Emanationism...