Thisraisesthequestion, WhydoesDarwinpresshistheorytotheseextremeconclusions? Whydoallhypothesesofderivationconvergesoinevitablytooneultimatepoint? Havingalreadyconsideredsomeofthereasonswhichsuggestorsupportthetheoryatitsoutset—whichmaycarryitasfarassuchsoundandexperiencednaturalistsasPictetallowthatitmaybetrue—perhapsasfarasDarwinhimselfunfoldsitintheintroductorypropositioncitedatthebeginningofthisarticle—,inthepropersenseoftheword, , ?Whatworkwillthishypothesisdotoestablishaclaimtobeadoptedinitscompleteness? Whyshouldatheorywhichmayplausiblyenoughaccountforthediversificationofthespeciesofeachspecialtypeorgenusbeexpandedintoageneralsystemfortheoriginationorsuccessivediversificationofallspecies,andallspecialtypesorforms, fromfourorfiveremoteprimordialforms, orperhapsfromone? Weacceptthetheoryofgravitationbecauseitexplainsallthefactsweknow, , forsimilarreasons; notbecauseitisproved—thusfaritisincapableofproof—butbecauseitisanaturaltheoreticaldeductionfromacceptedphysicallaws, isthoroughlycongruouswiththefacts, ? Ifso, howeverunproved, itwouldappeartobeatenablehypothesis, , fromtheconditionsofthecase, canneitherbeprovednordisprovedbydirectevidenceorexperiment, aretobetestedonlyindirectly, andthereforeimperfectly, bytryingtheirpowertoharmonizetheknownfacts, : Whatwillanhypothesisofthederivationofspeciesexplainwhichtheopposingviewleavesunexplained?
