The power of human language is of prime significance to Karl's philosophy, the philosophy of critical rationalism, and Karl's interest in some of the more striking illustrations of its role, such as the cases of Genie and of Helen Keller, was not incidental. Those who know his work know that in Logik der Forschung Karl solved once and for all Hume's problem of induction. The truly radical character of Karl's solution to the problem of induction has become clear only gradually, and to some not at all. Language is by far the most important product of exosomatic evolution, that is, of the evolution of external structures that need not die when the organism dies, and can be inherited in a modified form by the next generation. It is crucial to critical rationalism that the most salient features of philosophical theories are not those that relate to us but those that are as objective as are the theories themselves.