The phenomenon of consciousness has already been defined as the cognition or knowledge of the existence of self and of the Universe. The word also defines, as previously stated, a certain state or condition of the brain, in which the brain has this power of cognition of self-existence and of other simultaneous cognitions. This phenomenon occurs only as a property of certain living bodies and is present in them only during certain intervals of time. It is not essential to life and is probably not present at any time in certain species.
In most species of plants we have no positive evidence that the conscious state ever exists. There are at least two different kinds of cognition or knowledge:
- Cognitions of external relations, that is, things external to the brain, or sensation. This kind of knowledge comes from correlative internal relations produced in the brain by external relations through the organs of sense. These correlative internal relations are interpreted by the brain as cognitions of the external relations.
- Cognitions of internal relations: of those relations already existing in the brain and not caused by energy transmitted to the brain and not requiring the aid of sensory tracts or other transmitting organs, but originating entirely in the brain itself, e. g., memory. Sensation, or knowledge of external relations, is the fundamental cognition—the foundation on which all other cognitions are built. Without the cognitions of sensation there could be no previous cognition and, therefore, no recollection of a previous cognition. Without sensation and recollection there could be no reason, contemplation, thought or emotion.
***Excerpt from Charles John Reed: The Law of Vital Infusion and the Phenomenon of Consciousness