Group I. These belong to the life which biologists call organic or vegetative, as opposed to the life of relation. All these converge towards a single end, the fundamental act of life—nutrition. To simplify the matter as much as possible, let us divide this act into three stages: reception, transformation, and restitution. (1) The first only has any psychological interest, showing itself in consciousness by two very energetic needs—hunger and thirst. It is almost superfluous to say that these instincts pass beyond the bounds of psychology into the domain of sociology, where their function is a very important one, as is seen by the phenomena of dearth, famine, theft, crimes, cannibalism, deadly combats for the possession of a little water, etc. Their pathology is thus more instructive than one would think, because it states and resolves, as we shall see, in a simple form, the problem of whether the tendency is anterior to pleasure and pain. (2) The stage of transformation is purely physiological. It, too, shows itself in needs, of which the most pressing is that of breathing, an indispensable condition of the combustion of matter and the consequent interstitial exchanges. If air had to be acquired and conquered, like food, this instinct would show itself in consciousness, as do hunger and thirst; but this rarely happens (dyspnœa, asphyxia). Its pathology is not instructive, and only comprises individual peculiarities, such as always breathing either hot or cold air, sleeping with open windows, etc. (3) The stage of restitution outwards (secretions, excretions, etc.), though showing itself by instinctive movements, is only very indirectly connected with our subject; and though, in fact, _nothing_ which takes place in the organism is quite unconnected with psychology, we may pass this over in silence. Group II. These instincts belong to the so called relative life, and correspond to two stages—those of reception and restitution. The first stage is represented by all the forms of external perception, and comprises the tendencies connected with the exercise of each of our senses, the tendency of each sensory organ to fulfil its function: the eye tends to see, the hand to grasp and feel. These tendencies, if satisfied, are agreeable; if obstructed, unpleasant. Hence result pleasure and pain, but not emotions properly so called. The second stage is represented by all the forms of muscular movement, tendencies to action, to the production of noises, as in certain animals, to cries, vocalisation, gestures, and bodily attitudes. We have seen that all these things, in popular opinion, serve to express emotions, while, in our view, they are integral parts of them.