It would seem, therefore, that the pessimist psychology, in treating pleasure in a different way from pain, mistakes the true nature of both as simply "polar extremes"[171] of feeling, and prevents the argument being faced which has been brought forward to show the increasing correspondence of pleasure and life. * * * * * [Sidenote: (_cc_) the facts of human progress:] The failure of the psychological argument makes the whole burden of the proof of pessimism rest upon the argument from historical facts. And the attempt has been definitely made to show, from observation of the course of human affairs, that the progress of the world tends to misery. It is necessary, therefore, to ask whether it can be established that the facts included under the vague term "human progress" have a normal tendency either to increase pleasure or to act in the opposite way. Now progress is a characteristic both of the individual and of society; but pleasure only belongs to the former, so that an answer to the question whether individual progress tends to increase the surplus of pleasure over pain, still leaves unsettled the question as to the effect of social progress. [Sidenote: individual progress;] It seems evident that both the physical and mental development of the individual imply greater adaptability to, and correspondence with, the external world, and that, on account of this development, there is less unpleasant friction between outer and inner relations, and means are at hand for obtaining objects of desire with less exertion than formerly. But, at the same time, the increase of knowledge and of skill always implies not merely the means of satisfying old wants, but the creation of new ones: we see more of the evil in the world than our forefathers did, and there are more avenues by which it can approach us, if we have also more effective means for avoiding what we dislike. And, although knowledge brings with it not only the pleasure of gratified curiosity, but that recognition of a universal order which frees the mind from the evils bred by a belief in the fickleness of nature, yet this all-pervading sense of law has so regulated our beliefs and methods of research that science itself may seem to have lost the peculiar freshness of interest that belonged to its earlier stages; while the feelings called forth by a vision of the divine presence in the world, find but a poor substitute in the sublime region of "cosmic emotion." Further, the widening of the sympathetic feelings and their consequent activities, and the refinement of the whole sensitive nature by which it responds more quickly and accurately to emotional stimuli, have made the present generation more susceptible to both pain and pleasure than its predecessors. But Hartmann's argument that the duller nervous system of the savage races (Naturvölker) makes them happier than the civilised (Culturvölker),[172] leaves out of sight the new sources of