Traditionally, there are two ways of becoming aware that something exists, one by the senses, the other by what is called “introspection”, or what Kant called the “inner sense”. By means of introspection, it is maintained, we become aware of occurrences quite different in kind from those perceived through the outer senses. Occurrences known through introspection are traditionally called “mental”, and so are any other occurrences which intrinsically resemble them. Mental occurrences are traditionally of three main types, called knowing, willing, and feeling. “Feeling”, in this connection, means pleasure and unpleasure--we do not say “pleasure and pain”, because “pain” is an ambiguous word: it may stand for painful sensation, as when you say “I have a pain in my tooth”, or it may stand for the unpleasant character of the sensation. Roughly pleasure is a quality which makes you want an experience to continue, and unpleasure is the opposite quality which makes you want an experience to stop. However, I am not concerned to enlarge upon feeling at present. As for the other two kinds of mental occurrence, “knowing” and “willing” are recognised as too narrow to describe what is meant. Philosophers wish to include not only knowledge but also error, and not only the sort of knowledge that is expressed in beliefs but also the sort that occurs in perception. The word “cognition” or “cognitive state” is used to cover everything that could possibly be described as either knowledge or error; perception is _prima facie_ included, but pure sensation is more debatable. “Willing”, again, is too narrow a term. A term is required which will include desire and aversion, and generally those states of mind which lead up to action. These are all included under the head of “conation”, a technical term invented for this special purpose. Cognition and conation both have, in the orthodox theory, the property of being directed to an _object_. What you perceive or believe, what you desire or will, is something different from your state of mind. To take instances: you remember a past event, but your remembering occurs now; therefore your remembering is a different occurrence from what you remember. You will to move your arm, but the movement is a physical occurrence, and therefore obviously different from your volition. Many psychologists have taken this relation to an object as the essential characteristic of mind--notably the two Austrians Brentano and Meinong. Sometimes feeling also is regarded as having an object: it is held that we are pleased or displeased _at_ something. This view, however, has never won general acceptance, whereas the view that cognition and conation are directed to objects may be regarded as orthodox.