188 SECTIONAL ADDRESSES. 



as Praelector in Natural Sciences at St. John's College, and began 

 immediately tO' exercise a wonderful influence over the younger members 

 of the University by his fascinating lectm-es, his ' Sunday evenings,' 

 and above all by his ever-ready interest and sympathy. As he himself 

 wrote, after the war work ' which brought me into contact with the 

 real problems of life ... I felt that it was impossible for m© to 

 return to my life of detachment. ' And when a few months before his 

 death he was invited by the Labour Party to- &■ still more public sphere 

 of work, viz., tO' become a Parliamentary candidate representing the 

 University of London, once again he gave himself unsparingly. He 

 wrote at the time : ' To one whose life has been passed in scientific 

 research and education the prospect of entering practical politics can be 

 no light matter. But the times are soi o^minous, the outlook both for 

 O'ur own conntry and the world so black, that if others think I can 

 be O'f service in political life I cannot refuse.' On several occasions 

 subsequently he addressed interested London audiences, consisting 

 largely of his supporters, on the relations between Psychology and 

 Politics. It was one O'f these very lectures — on the Herd Instinct' — at 

 which it happened that I took the chair, \\hich was to have formed 

 the basis of his Presidential Address tO' you here to-day. 



Eivers's views on the so-called herd instinct were the natural outcome 

 of those which he had put forward during the preceding five years and 

 collected together in his ' Instinct and the Unconscious.' His aim in 

 writing this book was, as he says, ' to- provide a biological theory for 

 the psychoneuroses, ' to view the psychological from the physiological 

 standpoint. He maintained that an exact coiTCspondence holds 

 between the inhibition of thei physiologist and the repression of the 

 psychologist. He regarded mental disorders as mainly dependent on 

 the coming to the surface O'f older activities which had been previously 

 controlled or suppressed by the later products oi evolution. Here 

 Rivers went beyond adopting Hughlings Jackson's celebrated explana- 

 tion of the phenomena of nervo-us diseases as arising largely from the 

 release of lower-level activities frO'm higher-level controls. He further 

 supposed that these, lower-level activities represent earlier racial 

 activities held more or less in abeyance by activities later acquired. 

 This conception he derived from his work with Henry Head on 

 cutaneous sensibility. Rivers could see but ' two chief possibilities ' 

 of interpi'eting the phenomena disclosed in the study of Head's arm. 

 Either epicritic sensibility is protopathic sensibility in greater per- 

 fection, or else protopathic sensibility and epicritic sensibility represent 

 two distinct stages in the development of the nei-voiis system. Failing 

 to see any other explanation,- he adopted the second of these alternatives. 

 He supposed that at so^me period of evolution, when epicritic sensibility, 

 with its generally surface distribution, its high degree oi discrimination, 

 and its power of accurate localisation, made its appearance, the 

 previously existing protopathic sensibility, wdth its punctate distribution, 

 its ' all-or-nothing ' character, and its bro^ad radiating localisation, 

 became in part inhibited or 'suppressed,' in part blended or 'fused' 

 with the newly acquired sensibility so as tO' form ai useful product. 

 He supposed that the suppressed portion persisted in a. condition of 



