Existence exists—and the act of grasping that statement implies two corollary axioms: that something exists which one perceives and that one exists possessing consciousness, consciousness being the faculty of perceiving that which exists.
If nothing exists, there can be no consciousness: a consciousness with nothing to be conscious of is a contradiction in terms. A consciousness conscious of nothing but itself is a contradiction in terms: before it could identify itself as consciousness, it had to be conscious of something. If that which you claim to perceive does not exist, what you possess is not consciousness.
Whatever the degree of your knowledge, these two—existence and consciousness—are axioms you cannot escape, these two are the irreducible primaries implied in any action you undertake, in any part of your knowledge and in its sum, from the first ray of light you perceive at the start of your life to the widest erudition you might acquire at its end. Whether you know the shape of a pebble or the structure of a solar system, the axioms remain the same: that it exists and that you know it.
To exist is to be something, as distinguished from the nothing of non-existence, it is to be an entity of a specific nature made of specific attributes. Centuries ago, the man who was—no matter what his errors —the greatest of your philosophers, has stated the formula defining the concept of existence and the rule of all knowledge: A is A. A thing is itself. You have never grasped the meaning of his statement. I am here to complete it: Existence is Identity, Consciousness is Identification.
Whatever you choose to consider, be it an object, an attribute or an action, the law of identity remains the same. A leaf cannot be a stone at the same time, it cannot be all red and all green at the same time, it cannot freeze and burn at the same time. A is A. Or, if you wish it stated in simpler language: You cannot have your cake and eat it, too.
Are you seeking to know what is wrong with the world? All the disasters that have wrecked your world, came from your leaders' attempt to evade the fact that A is A. All the secret evil you dread to face within you and all the pain you have ever endured, came from your own attempt to evade the fact that A is A. The purpose of those who taught you to evade it, was to make you forget that Man is Man.
[...]
Reality is that which exists; the unreal does not exist; the unreal is merely that negation of existence which is the content of a human consciousness when it attempts to abandon reason. Truth is the recognition of reality; reason, man's only means of knowledge, is his only standard of truth.
Ayn Rand,
Atlas Shrugged
In other words, existence/reality has primacy over consciousness. Primacy of consciousness over reality is contradictory and retarded because in order for a consciousness to exist, reality must exist.
And I'm not telling you.
