Consciousness is aware or its own being aware of something. Whatever the faith ascribed to that something, the awareness of the awareness seems indubitable. It flashes out from the background at the slightest movement, it was always already there, and whatever certainty there can be in consciousness derives from its quickness. This is why centres of consciousness cannot be disconnected; disconnection belongs only to the object, the something, which is always a synthesis, to be immediately superceded by that flashing apperception which is unitary. So, 'transcendental unity of apperception' is a double tautology.