I. The Concept of Consciousness. § II. Condition of Ideas in Consciousness. § III. Perception and Apperception; Clearness and Distinctness of Ideas. § IV. Phenomena accompanying Apperception. § V. Attention. § VI. Self-consciousness.

WHAT is ‘consciousness’? Much attention has been devoted to this question in modern times both by philosophers and psychologists. There could be no doubt that the word denoted some phase or aspect of our mental life, and was not identical with any of the other concepts, like ‘idea,’ ‘feeling,’ ‘will,’ etc., which we apply to particular mental processes and states. So that the view naturally suggested itself that consciousness is a special mental condition, requiring to be defined by certain characteristic marks. And the feeling that it was necessary to oppose to consciousness an unconscious mental existence promoted this opinion. Ideas, affective processes, may vanish and then again appear. It is therefore inferred that after leaving consciousness they have continued to exist in an unconscious state, and at times return to their former: condition.