There are certain occurrences which we are in the habit of calling &quot;mental.&quot; Among these we may take as typical BELIEVING and DESIRING. The exact definition of the word &quot;mental&quot; will, I hope, emerge as the lectures proceed; for the present, I shall mean by it whatever occurrences would commonly be called mental.<br />I wish in these lectures to analyse as fully as I can what it is that really takes place when we, e.g. believe or desire. In this first lecture I shall be concerned to refute a theory which is widely held, and which I formerly held myself: the theory that the essence of everything mental is a certain quite peculiar something called &quot;consciousness,&quot; conceived either as a relation to objects, or as a pervading quality of psychical phenomena.<br />The reasons which I shall give against this theory will be mainly derived from previous authors. There are two sorts of reasons, which will divide my lecture into two parts:<br />(1) Direct reasons, derived from analysis and its difficulties;<br />(2) Indirect reasons, derived from observation of animals (comparative psychology) and of the insane and hysterical (psycho-analysis).