they have been openly discussed and approved. 'Idea' is a good vague neutral word, and was by Locke employed in the broadest generic way; but notwithstanding his authority it has not domesticated itself in the language so as to cover bodily sensations, and it moreover has no verb. 'Thought' would be by far the best word to use if it could be made to cover sensations. It has no opprobrious connotation such as 'feeling' has, and it immediately suggests the omnipresence of cognition (or reference to an object other than the mental state itself), which we shall soon see to be of the mental life's essence. But can the expression 'thought of a toothache' ever suggest to the reader the actual present pain itself? It is hardly possible; and we thus seem about to be forced back on some _pair_ of terms like Hume's 'impression and idea,' or Hamilton's 'presentation and representation,' or the ordinary 'feeling and thought,' if we wish to cover the whole ground. In this quandary we can make no definitive choice, but must, according to the convenience of the context, use sometimes one, sometimes another of the synonyms that have been mentioned. _My own partiality is for either FEELING or THOUGHT._ I shall probably often use both words in a wider sense than usual, and alternately startle two classes of readers by their unusual sound; but if the connection makes it clear that mental states at large, irrespective of their kind, are meant, this will do no harm, and may even do some good.[188] * * * * * _The inaccuracy of introspective observation_ has been made a subject of debate. It is important to gain some fixed ideas on this point before we proceed. The commonest spiritualistic opinion is that the Soul or _Subject_ of the mental life is a metaphysical entity, inaccessible to direct knowledge, and that the various mental states and operations of which we reflectively become aware are objects of an inner sense which does not lay hold of the real agent in itself, any more than sight or hearing gives us direct knowledge of matter in itself. From, this point of view introspection is, of course, incompetent to lay hold of anything more than the Soul's _phenomena_. But even then the question remains, How well can it know the phenomena themselves? Some authors take high ground here and claim for it a sort of infallibility. Thus Ueberweg: "When a mental image, as such, is the object of my apprehension, there is no meaning in seeking to distinguish its existence in my consciousness (in me) from its existence out of my consciousness (in itself); for the object apprehended is, in this case, one which does not even exist, as the objects of external perception do, in itself outside of my consciousness. It exists only within me."[189] And Brentano: