Interesting question!
I actually think CamC was on the right track when s/he said that because time and space are illusions neither came first. It's a horrible pretzel to get your mind into (some people enjoy contortions of a mental nature

), but the difference between the void (or in other words, the
unmanifest) and the creation (the
manifest) is only apparent for consciousness that is observing this infinite fractal we call reality from below the perspective of intelligent infinity. You see, above the level of finite perception, all POSSIBLE realities exist. Not one or two or a million, but an infinite number of combinations of matter and energy. So from one point of view, nothing was ever created and nothing will ever be destroyed. However, it may appear to in linear reality.
Everything exists, because nothingness does not exist. It can't exist, it is nothingness. The label of "nothingness" or "void" given to the "infinite lack there of" doesn't make it any more existent or real. But I guess realness is up for debate at this level of reality. It is so hard for us, as human beings, to think in a non linear way, outside of time and normal conceptions of space. So, infinite existence is balanced by infinite non-existence (the void). Consciousness, or energy, which everything that exists is made of, reflects this thoughtform of duality between positive (expansion/existence) and negative (contraction/non-existence) in everything from the macrocosm to the microcosm. Energy is the thoughtform of action. Entropy is the thoughtform of nonaction. This is where polarization and how energy flows comes into play and where it eventually takes you.
You can evolve towards the super awake half of the creator (consciousness), or the super asleep version of the creator (matter). You don't ever become completely one or the other forever, but you can come infinitely close. Imagine walking towards some place but everytime you take a step, the next step is half the distance the last one was. You never get there, but you can become infinitely close. That is the kind of situation we are dealing with here.
If you did somehow manage to become one or the other, self awareness would cease. The reason for this is because in order for consciousness (which is the backbone of existence) to remain conscious, there has to be something for it to be
conscious of. If you reached a state of all consciousness, you would have awareness of all things and there opposites combined, they would cancel each other out, and you would be left with nothing to percieve but perhaps raw energetic balance...that is, until by choice, the thoughtform of imbalance is thrown back into the mix which destabilizes infinity, in effect pressing the "reset button", causing "differences" to form once again, and starting individuation all over again.