What is the relation of these indefinable and unanalyzed stimuli to the feelings? Since the passions which surround the heart find their roots in the finest fibers of the physical structure, the degree to which these fibers are stimulated determines the degree to which the feelings will be excited and will express themselves. Love, courage, anger, and bravery are in proportion to the stimulus of the heart and the collaborating parts: “Die Innigkeit, Tiefe und Ausbreitung mit der wir Leidenschaften empfangen, verarbeiten und fortpflanzen macht uns zu den flachen oder tiefen Gefässen die wir sind.” The forcefulness of thought is likewise dependent upon the vigor of this obscure stimulus, for no thought, says he, can reach the brain unless feeling in its proper physical connection has preceded it. And just here our philosopher lays the very roots of individuality. The degree to which the fibers are stimulated is the beginning of the operations which will end in producing an aggregate of properties peculiar to an individual. II. SENSES By this inductive method, which develops fundamentally a philosophy of evolution, Herder finds that the senses are a nerve-structure developed to meet the waves of stimulus from without and feeling from within and to differentiate them more finely than did the fibers which worked only in a general way. But the law is the same. The nerves of every sense operate according to the same law by which the fibers contract and expand. The nerves advance to meet pleasant agreeable things, but recede from and resist unpleasant things. Now Herder observes that something other than the organ of sense and the external objects must operate to produce sensation in at least two of the senses. He sees a certain mental bond without which sight and hearing could not go to the object nor the object to the senses; this common substance, he says, is light, a substance which has the peculiarity of taking just so much from creation as the two end organs can receive. But this light as a medium is a requisite for the finer senses only. There are coarser senses, fibers, and stimuli which cannot be brought into action thus. They can feel only in themselves, for the object must come to them, touch them, and, to a certain extent, be one with them. Herder is explicit in connecting individual character with the senses. The contribution which each sense makes to the soul cannot with any two human beings be the same in kind, strength, depth, and breadth. There are many proofs of this. Seeing and hearing, which furnish most of the material for thinking, are seldom in one individual with the same degree of training or of natural force. This will not only account for inequalities of the senses evinced in all forms of expression in a single individual, but for such inequalities among groups and races. For, he continues, imaginative power in which thoughts and feelings disport themselves is made of the flowing together of sense impressions.