THE NEED FOR NEW KNOWLEDGE 



lished. Again, as far as I know, the analytic theory of numbers, 

 as such, has led to no practical consequences. Yet one must 

 think hard and long to find examples like this; and in so think- 

 ina, one is led to recognize that this is not quite the point. 

 These great intellectual developments, whether they will in time 

 lead to practical application or not, are continuous with and 

 contiguous to parts of science which have played an enormous 

 part in practice. The same methods as are developed in these 

 fields are part of the equipment of the trained physical scientist; 

 the same people who work in these fields may themselves be in- 

 volved in practical affairs, or may be the teachers and colleagues 

 of those who are. These circumstances derive from the fact that 

 between all parts of science, even those which seem to us 

 remote and unlike, there is a pervasive potential mutual 

 relevance, a relevance often somewhat overdescribed as the 

 unity of science. 



Even if it were determined that only such new knowledge 

 should be sought as would have practical consequences, or that 

 only such studies should be supported by public funds, we 

 should be poorly put to it to know how to carry out such de- 

 cisions. We are in general not very good at imagining what will 

 be the practical consequences of enquiry. We cannot be, 

 because if the enquiry is well conceived it will not merely come 

 up with a new answer; it will come up with something far more 

 valuable, which is a new question, one which had not been 

 thought of before. Out of such questions, and their progeny, the 

 growth of science and the growth of practice both arise. 



I should, of course, bitterly resist any limitation of science 

 to that which is potentially useful; and it is clear to me that no 

 very helpful limitation of this kind can in practice be applied. It 

 is therefore fortunate, as other speakers will surely establish, 

 that the costs of studying nature, in whatever appropriate form 

 and in all its branches, are so extraordinarily modest, compared 



