Twenty-three years have elapsed since William James startled the world with his article entitled “Does ‘consciousness’ exist?” In this article, reprinted in the volume called _Essays in Radical Empiricism_, he set out the view that “there is only one primal stuff or material in the world”, and that the word “consciousness” stands for a function, not an entity. He holds that there are “thoughts”, which perform the function of “knowing”, but that thoughts are not made of any different “stuff” from that of which material objects are made. He thus laid the foundations for what is called “neutral monism”, a view advocated by most American realists. This is the view advocated in the present volume. In this chapter, we have to ask ourselves whether there is anything that we can call “consciousness” in any sense involving a peculiar kind of stuff, or whether we can agree with William James that there is no “inner duplicity” in the stuff of the world as we know it, and that the separation of it into knowing and what is known does not represent a fundamental dualism. There are two very different meanings attached to the word “consciousness” by those who use it. On the one hand, we are said to be “conscious of” something; in this sense, “consciousness” is a relation. On the other hand, “consciousness” may be regarded as a quality of mental occurrences, not consisting in their relation to other things. Let us take the first view first, since, in discussing it, we shall find reasons for rejecting the second view. What is the relation we call being “conscious of” something? Take the difference between a person awake and a person asleep. The former reacts to all kinds of stimuli to which the latter does not react; we therefore say that the latter is not “conscious of” what is happening in his neighbourhood. But even if the sleeper does react in a fashion, for example, by turning away from the light, such a reaction does not fall within what is commonly regarded as “knowledge” or “awareness”; we should say that the sleeper turned over “unconsciously”. If he wakes up sufficiently to speak intelligently, for instance to address the disturber by name, we consider him “conscious”. So we do if we find that he remembers the incident next morning. But common sense does not regard any and every bodily movement in response to a stimulus as evidence of “consciousness”. There is no doubt, I think, that common sense regards certain kinds of response as evidence of some “mental” process caused by the stimulus, and regards the “consciousness” as residing in the inferred “mental” occurrence.