The _knowledge_ of right (what is allowed and commanded) and of wrong (what is forbidden) had been long since acquired. In the seventeenth month, e. g., a sense of cleanliness was strongly developed, and later (in the thirty-third month) the child could not, without lively protest, behold his nurse acting contrary to the directions that had been given to himself--e. g., putting the knife into her mouth or dipping bread into the milk. Emotions of this kind are less a proof of the existence of a sense of duty than of the _understanding_ that violations of well-known precepts have unpleasant consequences--i. e., that certain actions bring in their train pleasant feelings, while other acts bring unpleasant feelings. How long before the knowledge of words these emotions began to exist I have, unfortunately, not succeeded in determining. But in many of the above cases--and they might without difficulty be multiplied by diligent observation--there is not the least indication of any influence of spoken words. Whether no attempt at speaking has preceded, or whether a small collection of words may have been made, the cases of child-intelligence adduced in this chapter, observed by myself, prove that without knowledge of verbal language, and independently of it, the logical activity of the child attains a high degree of development, and no reason exists for explaining the intelligent actions of children who do not yet speak at all--i. e., do not yet clothe their ideas in words, but do already combine them with one another--as being different specifically from the intelligent (not instinctive) actions of sagacious orangs and chimpanzees. The difference consists far more in this, that the latter can not form so many, so clear, and so abstract conceptions, or so many and complicated combinations of ideas, as can the gifted human child in the society of human beings--_even before he has learned to speak_. When he has learned to speak, then the gap widens to such an extent that what before was in some respects almost the equal of humanity seems now a repulsive caricature of it. In order, then, to understand the real difference between brute and man, it is necessary to ascertain how a child and a brute animal may have ideas without words, and may combine them for an end: whether it is done, e. g., with memory-images, as in dreaming. And it is necessary also to investigate the _essential character of the process of learning to speak_. Concerning the first problem, which is of uncommon psychogenetic interest and practical importance, a solution seems to be promised in the investigation of the formation of concepts in the case of those born deaf, the so-called deaf and dumb children. On this point I offer first the words of a man of practical experience. The excellent superintendent of the Educational Institute for the Deaf and Dumb in Weimar, C. Oehlwein (1867), well says: