§ 1. Common Sensibility.—The pleasure and pain connected with organic sensations are of fundamental and allpervading importance in our mental life. Normally, these sensations are fused in a total mass of experience, which can only be very partially analysed into its components by attentive scrutiny. The membranes which line our internal organs are generally supplied by sensory nerves, which, from all parts of the body, are perpetually conducting a multitude of impressions to the central nervous system. On the resultant effect of these impulses it depends whether at any moment we feel well or ill, cross or complacent. By the nature of our organic sensations in the morning we can often predict whether the day's experiences are going to be agreeable or disagreeable. The feeling-tone of common sensibility determines in large measure the feeling-tone of more special experiences in the way of sensations, perceptions, and ideas. An incident which might be pleasant or but slightly disagreeable if we were feeling fresh and "fit," is apt to be intensely disagreeable if our organic functions are out of order. This is too wellknown a fact to need extended illustration. Smells and tastes which are agreeable to the healthy person may be highly unpleasant to the invalid. After a full meal, food which was previously delicious may become almost nauseous; even the idea of it may be unpleasant. The very thought of smoking a pipe in certain states of body may be repellent in the case of persons who usually enjoy the use of tobacco. The profound alteration of organic conditions which accompanies pregnancy produces curious ''longings" and repugnances for articles of food. It thus appears that organic sensations influence the whole state of the central nervous system.* The neural processes connected with special sensations are more definitely restricted and localised. The experiences due to common sensibility are diffusive in their character. They give to the nervous system a certain general predisposition, and on the psychical side produce a certain general mood or temper.

*Besides receiving sensory impressions from the internal organs, the central nervous system is also directly affected by general organic conditions, and in particular by the character and amount of the bloodsupply which flows to it. This factor must also contribute to determine the general nature of experience as pleasant or unpleasant. Its relative importance as compared with the more indirect effect of sensory impressions upon the internal organs is difficult to estimate.

By reflective scrutiny it is possible, as we have said, to detect special components of the total complex of organic sensation, such as those due to the heartbeat, and respiration, and the shiverings of cold or glows of warmth arising from contraction or dilatation of the bloodvessels at the surface of the body. But there are occasions when no special effort of attention is required to detect an organic sensation. The experiences immediately due to a toothache, to a colic, to muscular cramp, to a burn, a bruise, or a blow, usually compel attention, whatever other interests may compete with them. When one organic sensation detaches itself from the mass of common sensibility, it is apt to be overwhelmingly obtrusive. Such intense experiences are much more often painful than pleasant; but they also occur in agreeable phases. In general, the satisfaction of organic cravings, such as hunger and thirst, may be intensely agreeable. The peculiarly disagreeable character of most organic sensations which are intense enough to detach themselves from the general mass, is marked by the usage of popular language which applies to them in a restricted and distinctive sense the word pains. A bitter taste or a discord may be disagreeable, but it is not usually called a pain. On the other hand, we currently speak of the pains of hunger, of scalding or burning, or of toothache. The reason is that the main importance of such experiences lies in their intrinsic feeling-tone. They have comparatively little value for cognitive consciousness. They contribute comparatively little to the discrimination of the qualities of external bodies; and they yield only more or less vague information about the condition of our own bodies. When we have received a wound, we have to look at it to find out its precise character and the proper mode of treating it. The pain-sensation itself does not help us much.

It must be noted that those sensations which are in popular language called, by a distinctive application of the word, pains, have other characteristics besides their mere unpleasantness. The feeling-tone does not exist in abstract purity: it is always the feeling-tone of some sensation having a more or less determinate character of its own. It is through the character of the accompanying sensation that we are able to distinguish different kinds of organic pain or pleasure. Thus we discriminate from each other stinging, piercing, gnawing, crushing, beating, shooting, burning, and innumerable other kinds of pain. Hence it is possible to compare pain-sensations in other respects than the intensity of their painfullness. The points of agreement and difference are to a large extent to be found in the temporal and local distribution of the constituents of a complex experience. Local distribution is marked by such terms as pricking, shooting. Temporal sequence and rhythmic alternation are marked by such terms as throbbing, beating, and the like. These differentiating qualities which we use in describing the varieties of pain-sensation have usually little cognitive value of any other kind. So far as cognitive consciousness is concerned, their main function is fulfilled in enabling us to detect and express the difference between one kind of pain and another. It is therefore natural that in naming them we should apply to all indifferently the common word pain. But it is better to speak of pain-sensations than of pain, in order to indicate that something besides mere unpleasantness is involved. Markedly analogous experiences may also occur without any intensely disagreeable feeling-tone. A slight burn may retain much of the peculiar prickly, pungent, quality of the original sensation when the painfulness has almost or quite disappeared. So it is possible occasionally to detect the peculiar throb characteristic of a toothache, and the tenderness of the gum, when the acutely disagreeable phase of the experience has passed away or has not yet arrived. Hunger is usually unpleasant, but sometimes the beginning of it does not appear to be so.