The particular rules of morality may and must change; but the highest principle of all morality is changeless. From the purest moral feeling came Schiller's words: "Live with thy generation, but be not its creature; serve thy contemporaries, but in that which they need, not that which they prize. Without having shared their guilt, share with noble resignation their punishments, and yield thyself freely to the yoke which they both illy could do without and illy bear. By the steadfast courage with which thou refusest their pleasure, thou shalt prove to them that it is not cowardice which causes thy submission." In these three sentences there lies a whole system of ethics. In the will to good, indivisible from a feeling of freedom, of which no power on earth can rob us, lies true happiness. For mind, as for matter, the law of the indestructibility of force, of work, is true. That which appears as force or energy is motion; every impulse to motion is motion, and only in so far as it appears, can the quantity of motion, force, energy, increase or diminish; as a matter of fact, it always remains the same. But just as the activity and force of matter increase with its differentiation, so the activity and energy of the mind increase with intelligence. It is through intelligence that we come to a comprehension of the distinction between good and evil, and through intelligence that we are able to increase social prosperity, and so morality. There are no innate, primary human rights; there are only acquired rights which man has gained for himself in the process of development. If we were to express negatively the end which mankind sets itself, we should define it as the greatest possible reduction of pain. Conscious existence is accompanied by a feeling of pleasure; but the general progress heedlessly overrides the individual being, and we therefore have to erect barriers against the stream which thus turns pleasure into pain. Pain and pleasure are relative to the individual. Every sensation is pleasurable as long as it does not exceed in strength a certain limit corresponding, in each case, to the nature of the individual. Since, however, every sensation becomes, by perception, feeling, thought appears as a modifying factor in all pain which does not arise from too extreme physical injury. The manner in which our perceptions, thought-images, are formed, the store of thought-images and concepts which we possess, and hence our thought-capacity, combined with the extent and clearness of our knowledge, are decisive not only with respect to the avoidance of pain and attainment of pleasure, but also with respect to our attitude towards pain and pleasure in general; every pain and every pleasure has, in the last analysis, such worth alone as we attribute to it. The universalization of true education, the increase of intelligence, is, therefore, the means by which man's lot may be bettered.