The significance of that 'absolute commandment', know thyself — whether we look at it in itself or under the historical circumstances of its first utterance — is not to promote mere self-knowledge in respect of the particular capacities, character, propensities, and foibles of the single self. The knowledge it commands means that of man's genuine reality — of what is essentially and ultimately true and real — of spirit as the true and essential being.
Encyclopedia of the Philosophical Sciences (1816)