Root meaning: The condition of knowing with certainty what something is.
Conventional: Being aware of or possessing information and concepts.
ACIM: The heavenly condition of knowing reality through direct and total union with it, unmediated by physical senses or mental interpretation. Knowledge and perception are mutually exclusive, for perception involves a separation between subject and object, knower and known. This makes certainty impossible. Yet knowledge is completely certain and without question. Thus it does not change and hence it is timeless. It is total, having no degrees. In it each part is the whole. It is completely non-specific, abstract. It contains no opposites, no contrast and no comparisons. It cannot be learned, for learning applies only to perception, where information enters from the outside. It can only be remembered. This happens when we reach the state of true perception, which contains no opposition to knowledge. The goal of the Course is readiness for knowledge, not knowledge itself (see T-18.IX.11). See T-3.III,IV,V, T-5.I.6-7, T-6.II.7.