Whether pleasure depends upon increase of vital energy, or upon unimpeded or medium functioning, it must be subject to modification along with the conditions under which life may continue and increase, or the modes of activity which may be carried on without opposition and in moderation. This constant modification of the objects in which one takes pleasure, or which give one pain, is, indeed, a fact which must be admitted by any theory of feeling. A state of mind may be at first pleasurable; but, if it be long-continued, the pleasure will give way to the pain of monotony. The same is true of a painful state of mind: its continuance does not prolong the same intensity of painful consciousness, but the sensibility becomes dulled and the pain diminishes. The transition is still more striking in the case of motor activities. In learning to walk, or to ride, or to play any instrument, the first experiences are those of painful effort. Gradually, however, the co-ordinations of movement required entail less and less pain, till the feeling passes over into its opposite, and we have a pleasurable sense of successful effort and well-adapted functioning. But, just as pain gave way to pleasure, so pleasure itself subsides, the action becomes merely reflex and passes out of consciousness altogether, unless it be so long continued as to produce fatigue--that is, pain. Habit, as Dumont remarks,[184] intensifies perceptions, but weakens pleasure and pain. [Sidenote: suggests that feeling depends on objective intensity.]