FromMill’sconstantinsistenceuponthepowerofassociationandtheempiricalcharacterofallknowledge，itmightbeinferredthatevenscientificprogressisprecariousandunstable。ToBucklethedevelopmentofscientificknowledgeseemstobeinevitable，ifonlythemindisallowedtoworkfreely。Themostconspicuousfactsofthedaygaveforcetohisconviction。Theenormouschangesinthewholeconstitutionofsocietywereduetotheadvanceofmechanicaldiscoveriesandtothetriumphoffree-traders。WattandAdamSmith，notthereligiouspreachers，representtherealtransformingforce。Thesteam-enginehasalteredthewholepositionofthehumanrace。ThesermonsofMethodistsandCatholicshavelefttheaveragemanjustwherehewas。Napoleonwasagreatcriminal，andWilberforce，perhaps，agreatphilanthropist。Theirinfluencehasbeentransitory，whilethescientificinventorshavesetupchangeswhichwillcontinuetogatherforceastheagesroll。
Thetruthcontainedinthis，again，seemstobeUndeniable。
Modifythe’environment’andyourorganismismodifiedthroughout。Altertheclimate，thesoil，theamountoffertileland，andthewholestateofmankindwillbealtered。That，again，hasbeenvirtuallyachievedbymoderndiscoveries。Thoughthenaturalforcesmaybethesame，ourrelationtothemhasbeenaltered；and，ifmorefertilesoilhasnotbeenwroughtintoexistence，thefertilesoilhasbeenbrought，wemaysay，nearertoourdoors。Moreover，thechangehasbeenprimarilyduetoscientificdiscoveryandnottoanymoralchange；orthemoralchanges，whatevertheymaybe，havebeentheconsequence，notthecause。SofarasBuckleemphasisedthisaspect，hewasclearlyinsistinguponatruthwhichrequiresrecognition。Thequestioniswhatbearingthishasuponthephilosophyofhistory，andwhetheritjustifiesusindiscardingtheinfluenceofthe’moral’elementinbuildingupthesocialstructure。
Thegeneraldoctrineleadstotheconclusionthattheessentialdifferencebetweentwostagesofhistoryisthedifferencebetweenthequantityofknowledgepossessedanditsdiffusionthroughoutallclasses。ThatisreallyBuckle’scontention，fromwhichallhisconclusionsarededucible。The’totalityofhumanactions，’ashesays，is’governedbythetotalityofhumanknowledge；44*or，asheelsewhereputsit，45*thehistoryofevery’civilisedcountryisthehistoryofitsintellectualdevelopment。’Ifearlysocietiesaregovernedbythe’physicallaws，’latersocietiesaregovernedbytheactionofthoselawsuponourminds，andtheactionisthusprofoundlymodifiedasourknowledgeofthelawsextends。The’environment’hasadifferentrelationtous，butremainstheultimateandindependentdeterminant。Ifthisbethewholetruth，itwouldfollowthatwemightwritethehistoryofmankindbywritingthehistoryofscience。Allotherphenomenawouldbesimplydeducibleascorollariesfromthestateofknowledge。
Comtehadsuggestedthathistorymightbewrittenwithoutmentioningthenamesofindividuals。OnBuckle’sassumption，historymaydealsimplywiththegrowthofscientificideas；and，therefore，weneednottakeintoaccountthemoralideasorallthecomplexsystemofactionswhichcomeundertheheadofthewillandtheemotionsinpsychologicaltreatises。