▁time ▁equal ▁to ▁an ▁acceler ated ▁body ▁whose ▁velocity ▁is ▁half ▁the ▁final ▁speed ▁of ▁the ▁acceler ated ▁body . ▁They ▁also ▁demonstrated ▁this ▁theorem — the ▁ess ence ▁of ▁" The ▁Law ▁of ▁Fall ing ▁Bod ies " — long ▁before ▁Gal ile o , ▁who ▁has ▁got ten ▁the ▁credit ▁for ▁this . ▁▁▁ ▁In ▁his ▁turn , ▁N icole ▁O res me ▁showed ▁that ▁the ▁reasons ▁proposed ▁by ▁the ▁physics ▁of ▁Arist ot le ▁against ▁the ▁movement ▁of ▁the ▁Earth ▁were ▁not ▁valid ▁and ▁ad du ced ▁the ▁argument ▁of ▁simplicity ▁for ▁the ▁theory ▁that ▁the ▁Earth ▁moves , ▁and ▁not ▁the ▁heav ens . ▁Despite ▁this ▁argument ▁in ▁favor ▁of ▁the ▁Earth ' s ▁motion , ▁O res me ▁fell ▁back ▁on ▁the ▁commonly ▁held ▁opinion ▁that ▁" every one ▁maintain s , ▁and ▁I ▁think ▁myself , ▁that ▁the ▁heav ens ▁do ▁move ▁and ▁not ▁the ▁earth ." ▁ ▁The ▁historian ▁of ▁science ▁Ron ald ▁Num bers ▁notes ▁that ▁the ▁modern ▁scientific ▁assumption ▁of ▁method ological ▁natural ism ▁can ▁be ▁also ▁trac ed ▁back ▁to ▁the ▁work ▁of ▁these ▁medieval ▁think ers : ▁ ▁However , ▁a ▁series ▁of ▁events ▁that ▁would ▁be ▁known ▁as ▁the ▁Cris is ▁of ▁the ▁Late ▁Middle ▁A ges ▁was ▁under ▁its ▁way . ▁When ▁came ▁the ▁Black ▁Death ▁of ▁ 1 3 4 8 , ▁it ▁se aled ▁a ▁sudden ▁end ▁to ▁the ▁previous ▁period ▁of ▁scientific ▁progress . ▁The ▁pl ague ▁killed ▁a ▁third ▁of ▁the ▁people ▁in ▁Europe , ▁especially