▁Cambridge , ▁he ▁wrote ▁to ▁his ▁sister ▁that ▁" my ▁head ▁is ▁running ▁about ▁the ▁Trop ics : ▁in ▁the ▁morning ▁I ▁go ▁and ▁gaz e ▁at ▁Pal m ▁trees ▁in ▁the ▁hot - house ▁and ▁come ▁home ▁and ▁read ▁H umb old t : ▁my ▁enthus ias m ▁is ▁so ▁great ▁that ▁I ▁cannot ▁hardly ▁sit ▁still ▁on ▁my ▁chair . ▁H ens low ▁& ▁other ▁D ons ▁give ▁us ▁great ▁credit ▁for ▁our ▁plan : ▁H ens low ▁promises ▁to ▁cr am ▁me ▁in ▁ge ology ". ▁He ▁was ▁studying ▁Spanish ▁language , ▁and ▁was ▁in ▁" a ▁Trop ical ▁g low ". ▁ ▁H ens low ▁introduced ▁Dar win ▁to ▁the ▁great ▁ge ologist ▁the ▁Rev d . ▁Adam ▁Sed g wick ▁who ▁had ▁been ▁his ▁own ▁t utor , ▁and ▁shared ▁views ▁on ▁religion , ▁politics ▁and ▁mor als . ▁Dar win ▁was ▁fired ▁up ▁by ▁Sed g wick ' s ▁Spring ▁course ▁of ▁" e quest rian ▁out ings " ▁with ▁its ▁v istas ▁of ▁the ▁grande ur ▁of ▁God ' s ▁creation , ▁so ▁much ▁of ▁which ▁was ▁yet ▁un expl ored . ▁He ▁exclaimed , ▁" What ▁a ▁capital ▁hand ▁is ▁S edge wick ▁for ▁drawing ▁large ▁che ques ▁upon ▁the ▁Bank ▁of ▁Time ! ". ▁When ▁Sed g wick ▁mentioned ▁the ▁effects ▁of ▁a ▁local ▁spring ▁from ▁a ▁ch alk ▁hill ▁depos iting ▁l ime ▁on ▁tw igs , ▁Charles ▁rode ▁out ▁to ▁find ▁the ▁spring ▁and ▁threw ▁a ▁bush ▁in , ▁then ▁later ▁brought