are perceived, and the memory-images of them, that is, accordingly, memory-images of separate perceptions, are so firmly associated that, where only one appears in the midst of entirely new impressions, the concept yet emerges, because all the other images appear along with it. Language is not required for this. Up to this point, those born deaf behave exactly like infants that have all the senses, and like some animals that form concepts. These few first ideas, namely, the individual ideas, or sense-intuitions that are generated by the first perceptions, and the simple general ideas (of a lower order), or concepts, arising out of these--the concepts of the child as yet without language, of microcephali also, of deaf-mutes, and of the higher animals--have now this peculiarity, that they have all been formed exactly in this way by the parents and the grandparents and the representatives of the successive generations (such notions as those of "food," "breast"). These concepts are not innate; because no idea can be innate, for the reason that several peripheral impressions are necessary for the formation of even a single perception. They are, however, inherited. Just as the teeth and the beard are not usually innate in man, but come and grow like those of the parents and are already implanted, piece for piece, in the new-born child, and are thus hereditary, so the first ideas of the infant, his first concepts, which arise unconsciously, without volition and without the possibility of inhibition, in every individual in the same way, must be called hereditary. Different as are the teeth from the germs of teeth in the newly-born, so different are the man's concepts, clear, sharply defined by words, from the child's ill-defined, obscure concepts, which arise quite independently of all language (of word, look, or gesture). In this wise the old doctrine of "innate ideas" becomes clear. Ideas or thoughts are themselves either representations or combinations of representations. They thus presuppose perceptions, and can not accordingly be innate, but may some of them be inherited, those, viz., which at first, by virtue of the likeness between the brain of the child and that of the parent, and of the similarity between the external circumstances of the beginnings of life in child and parent, always arise in the same manner. The principal thing is the innate aptitude to perceive things and to form ideas, i. e., the innate intellect. By aptitude (Anlage), however, can be understood nothing else at present than a manner of reacting, a sort of capability or excitability, impressed upon the central organs of the nervous system after repeated association of nervous excitations (through a great many generations in the same way).