In his “Acceptance speech for the association’s distinguished service award”:
Since my early days in Gottingen I have been concerned with “Applied Mathematics.” Yet until today I have not been able to define what the word means or should mean. On the contrary, I have become more and more wary of semantic definitions; they seem futile, and even dangerously restrictive.
…Only later, when specialization narrowed the angle of vision for everybody, did emphatic purism emerge. High priests of beauty and purity displayed an attitude of cool disinterest in mathematics which was not directed towards “the glory of the human mind.”
…I believe that it is vital to counteract these dangerous tendencies by fighting over-specialization and fragmentation of mathematics and by a vigorous effort at building bridges between the diverging mathematical fields as well as between mathematics and other sciences and human intellectual activities.
Mathematical Biology 