It must be noted that Herder does not regard these original “forces” as constituted by the senses; they are prior to and more fundamental than the senses. The phenomenon _Reiz_, stimulus, which causes the smallest fiber either in plant or animal to contract or expand, repeats itself in the nerves of each one of the senses. But this _Reiz_ is in the beginning, and without it there would be no _Kräfte_, no nerve, no sense organ. This _Reiz_, then, is identical with the innate forces, _Kräfte_. They control and direct the development of the senses and are, therefore, the very beginning of that variation in sense functioning which initiates individuality. It is in the treatment of these original _Kräfte_ that Herder gives his own turn to Leibniz’ theory of the monad. The principle of the monad was highly abstract, and when Herder took it over he gave to it a more concrete application. It became the principle of innate and varying potentialities. The monad was not controlled and directed by a force outside itself, according to Herder, but by a power within, and as the power within was never exactly alike in any two beings, no two could develop just alike. Here are Herder’s foundations for individuality and personality. A perfection resulting from the unfolding of the content of the individual life and the shaping of its originality are seen in Shaftesbury’s thought when he makes morality consist of the rich and full expression of individual powers in a beautiful and sovereign personality. The individual system as seen in one man in all its physical and mental elements is related to something external to himself. Altruistic inclinations are an important part of the natural endowment of every human being. Now Herder sees that this unfettered development of natural endowments will come to its fullest only in relations to others. It is the essence of his _Humanität_. He goes further than Shaftesbury in that he finds in this tie, which unites the individual to the group, that which is universal and fundamental. He endows his _Volk_ with sentiments which are universal and fundamental. It is this universal and fundamental which makes such expressions as “Hamlet’s soliloquy” find a place among the songs of Herder’s _Volk_. We have seen that when Herder lays emphasis on the feelings, when he is opposed to arbitrary and restrictive government, when he elevates the crude and primitive, his system of thought is in agreement with that of Rousseau. But Herder makes an advance in seeking standards in processes actually or believed to be found in Nature. His line of investigation in history, art, and philosophy will be by way of the natural man, i.e., the primitive. His _Volk_, then, because of their power to express their personality freely, give him a theory of art; art must be an expression of personality.