Donotallowyourselvestobemisledbythecommonnotionthatanhypothesisisuntrustworthysimplybecauseitisanhypothesis。Itisoftenurged，inrespecttosomescientificconclusion，that，afterall，itisonlyanhypothesis。Butwhatmorehavewetoguideusinnine—tenthsofthemostimportantaffairsofdailylifethanhypotheses，andoftenveryill—basedones？Sothatinscience，wheretheevidenceofanhypothesisissubjectedtothemostrigidexamination，wemayrightlypursuethesamecourse。Youmayhavehypothesesandhypotheses。Amanmaysay，ifhelikes，thatthemoonismadeofgreencheese：thatisanhypothesis。Butanotherman，whohasdevotedagreatdealoftimeandattentiontothesubject，andavailedhimselfofthemostpowerfultelescopesandtheresultsoftheobservationsofothers，declaresthatinhisopinionitisprobablycomposedofmaterialsverysimilartothoseofwhichourownearthismadeup：andthatisalsoonlyanhypothesis。ButIneednottellyouthatthereisanenormousdifferenceinthevalueofthetwohypotheses。Thatonewhichisbasedonsoundscientificknowledgeissuretohaveacorrespondingvalue；andthatwhichisamerehastyrandomguessislikelytohavebutlittlevalue。EverygreatstepinourprogressindiscoveringcauseshasbeenmadeinexactlythesamewayasthatwhichI
havedetailedtoyou。Apersonobservingtheoccurrenceofcertainfactsandphenomenaasks，naturallyenough，whatprocess，whatkindofoperationknowntooccurinnatureappliedtotheparticularcase，willunravelandexplainthemystery？Henceyouhavethescientifichypothesis；anditsvaluewillbeproportionatetothecareandcompletenesswithwhichitsbasishadbeentestedandverified。Itisinthesemattersasinthecommonestaffairsofpracticallife：theguessofthefoolwillbefolly，whiletheguessofthewisemanwillcontainwisdom。Inallcases，youseethatthevalueoftheresultdependsonthepatienceandfaithfulnesswithwhichtheinvestigatorappliestohishypothesiseverypossiblekindofverification。
IdaresayImayhavetoreturntothispointby—and—by；buthavingdealtthusfarwithourlogicalmethods，Imustnowturntosomethingwhich，perhaps，youmayconsidermoreinteresting，or，atanyrate，moretangible。Butinrealitytherearebutfewthingsthatcanbemoreimportantforyoutounderstandthanthementalprocessesandthemeansbywhichweobtainscientificconclusionsandtheories。1Havinggrantedthattheinquiryisaproperone，andhavingdeterminedonthenatureofthemethodswearetopursueandwhichonlycanleadtosuccess，Imustnowturntotheconsiderationofourknowledgeofthenatureoftheprocesseswhichhaveresultedinthepresentconditionoforganicnature。
Here，letmesayatonce，lestsomeofyoumisunderstandme，thatIhaveextremelylittletoreport。Thequestionofhowthepresentconditionoforganicnaturecameabout，resolvesitselfintotwoquestions。Thefirstis：Howhasorganicorlivingmattercommenceditsexistence？Andthesecondis：Howhasitbeenperpetuated？OnthesecondquestionI
shallhavemoretosayhereafter。Butonthefirstone，whatInowhavetosaywillbeforthemostpartofanegativecharacter。