The conscious part of the mind, which perceives, experiences, chooses (thus, in the Course this term does not denote a general principle or substance that pervades all levels of mind). “Consciousness is…the domain of the ego” (T-3.IV.2:2). Consciousness can receive messages from the ego, which is buried in the unconscious, or from the Holy Spirit, Who is also outside the conscious mind. It must choose between these two voices. It can be trained to experience miracles and see the real world. But it is inherently perceptual (subject-object oriented) and cannot reach knowledge. See C-1.7.