accompany it! From these facts and from many others of the same kind we believe we can deduce the following conclusion: our consciousness of an increase of muscular effort is reducible to the twofold perception of a greater number of peripheral sensations, and of a qualitative change occurring in some of them. [Sidenote: The same definition of intensity applies to superficial efforts, deep-seated feelings and states intermediate between the two.] We are thus led to define the intensity of a superficial effort in the same way as that of a cases there is a qualitative progress and an increasing complexity, indistinctly perceived. But consciousness, accustomed to think in terms of space and to translate its thoughts into words, will denote the feeling by a single word and will localize the effort at the exact point where it yields a useful result: it will then become aware of an effort which is always of the same nature and increases at the spot assigned to it, and a feeling which, retaining the same name, grows without changing its nature. Now, the same illusion of consciousness is likely to be met with again in the case of the states which are intermediate between superficial efforts and deep-seated feelings. A large number of psychic states are accompanied, in fact, by muscular contractions and peripheral sensations. Sometimes these superficial elements are co-ordinated by a purely speculative idea, sometimes by an idea of a practical order. In the first case there is intellectual effort or attention; in the second we have the emotions which may be called violent or acute: anger, terror, and certain varieties of joy, sorrow, passion and desire. Let us show briefly that the same definition of intensity applies to these intermediate states. [Sidenote: The intermediate states. Attention and its relation to muscular contraction.]