▁might ▁also ▁be ▁destroyed , ▁because ▁they ▁could ▁not ▁be ▁sold , ▁or ▁because ▁they ▁did ▁not ▁make ▁money . ▁Sol ving ▁the ▁crisis ▁meant ▁re organ izing ▁production ▁and ▁trade , ▁to ▁meet ▁the ▁new ▁requirements ▁for ▁prof itable ▁sales . ▁Usually , ▁cr ises ▁were ▁happening ▁all ▁the ▁time ▁somewhere ▁in ▁the ▁capital ist ▁economy , ▁but ▁those ▁cr ises ▁were ▁limited ▁to ▁specific ▁indust ries ▁going ▁b ust ▁– ▁such ▁cr ises ▁normally ▁did ▁not ▁spread ▁to ▁the ▁whole ▁economy . ▁However , ▁at ▁some ▁point , ▁the ▁crisis ▁of ▁particular ▁branches ▁of ▁activity ▁could ▁set ▁off ▁a ▁chain - re action ▁which ▁would ▁spread ▁to ▁the ▁whole ▁economy . ▁ ▁Marx ▁himself ▁never ▁developed ▁a ▁substant ive ▁theory ▁of ▁capital ist ▁cr ises , ▁beyond ▁comment ing ▁about ▁the ▁economic ▁cr ises ▁he ▁was ▁able ▁to ▁observe ▁himself . ▁His ▁main ▁claim ▁was ▁that ▁the ▁cr ises ▁are ▁system - im man ent ▁( due ▁to ▁end ogen ous ▁causes ), ▁and ▁not ▁an ▁accident al ▁aber r ation , ▁i . e . ▁they ▁are ▁a ▁necessary ▁feature ▁of ▁capital ist ▁development . ▁A ▁large ▁Marx ist ▁literature ▁on ▁" c ris is ▁theory " ▁now ad ays ▁exists , ▁in ▁which ▁different ▁authors ▁defend ▁various ▁ideas ▁about ▁the ▁" ult imate " ▁causes ▁of ▁capital ist ▁cr ises ▁( see ▁also ▁crisis ▁theory ) ▁– ▁bas ing ▁themselves ▁on ▁a ▁few ▁scattered ▁comments ▁by ▁Marx ▁on ▁the ▁topic . ▁Such ▁theories ▁are ▁very ▁difficult ▁to ▁prove ▁scientific