PROFESSOR AT KONIGSBERG 139 



purged of metaphysics, will still remain as the vast field of 

 knowledge of mental and psychical processes, and the laws 

 that govern them, and that it alone can provide the scientific 

 worker with the necessary insight into the potentialities of the 

 instrument with which he works the human mind a letter 

 written twenty years later to Kick shows that the development 

 of philosophy, for which Helmholtz longed, and strove on the 

 lines of his theory of knowledge, was slow to the last degree 

 in its evolution : 



' I believe that philosophy will only be reinstated when it 

 turns with zeal and energy to the investigation of epistemo- 

 logical processes and of scientific methods. There it has a 

 real and a legitimate task. The construction of metaphysical 

 hypotheses is vanity. Most essential of all in this critical 

 investigation is the exact knowledge of the processes of sense- 

 perception. . . . Philosophy has been at a standstill because 

 it was exclusively in the hands of the philologists and theo- 

 logians, and has so far imbibed no new life from the vigorous 

 development of the natural sciences. Hence it has been 

 almost entirely confined to the history of philosophy. I 

 believe that any German University that had courage to 

 appoint a scientific man with an inclination for philosophy to 

 its Chair of Philosophy would confer a lasting benefit on 

 German science.' 



The lecture on 'The Interaction of Natural Forces' had 

 not merely treated of the Law of the Conservation of Energy 

 in a generally intelligible form, but had developed a series 

 of totally new consequences for the constitution of the uni- 

 verse from this standpoint, so that it represented another 

 distinct scientific achievement. In like manner the lecture on 

 ' Human Vision ', which set out with the review and interpre- 

 tation of the laws he had discovered in physiological optics, 

 went on, in bringing ( an offering of respect and veneration ' 

 to Kant, to develop the philosophical consequences of his 

 discoveries, which were recognized ere long as the first 

 principles of the modern theory of knowledge. Helmholtz's 

 interest in epistemological questions had been awakened in 

 early days, when his father, who had imbibed a deep impres- 

 sion of Fichte's idealism, held discussions upon the profoundest 

 problems of speculative philosophy with his colleagues, who 



