Although all beings are intrinsically of the nature of the Supreme, few Realize it. Instead of Unity, there is duality. This duality is the result of a false self, generally referred to as the "ego". The "ego" maintains its existence by denying contents that are uncomfortable to it, and clinging to contents that it narcissistically identifies with. The contents it denies are called the Shadow, and the way it denies them - that is, its defenmse mechanisms - are through projecting the contents of the shadow onto others. This projection is teh opposite of true selflessness or empathy. At the same time it also projects its positive contents onto people and thinsg it identifies with, such as family, country, religion, peers, in-group, hero-figure, etc
Thus ordinary or samsaric consciousness is the result of a dichotomy between the false or narcissistic self (Ego), and the false not-self (Shadow).
The following diagram from an early book by Ken Wilber ( The Spectrum of Consciousness) presents a Transpersonal-Psychology based (itself in turn Jungian based) paradigm in which the originally unlimited consciousness limits itself through a series of dualities.
Here different psychologies pertain to different levels of duality (Wilber was later to reject this model in favour of a developmental one inspired by Da Free John). Although I don't agree with all the details, I do find this a useful diagram
It is this duality that defines our existence, and that remains until the atomistic recoil from the Source is rejected and Realization occurs. There are however a number of intermediate stages, as portrayed here:
note: the above represents a simplistic linear interpretation only; in fact all these stages interact and overlap. Rarely do all these levels develop at the same time, and the Integral/Divine Realization encompasses all of them.