Apartfromnaturalconditions，suchasfertilityofthesoil，&C。，andfromtheskillofindependentandisolatedproducers（shownratherqualitativelyinthegoodnessthanquantitativelyinthemassoftheirproducts），thedegreeofproductivityoflabour，inagivensociety，isexpressedintherelativeextentofthemeansofproductionthatonelabourer，duringagiventime，withthesametensionoflabour—power，turnsintoproducts。Themassofthemeansofproductionwhichhethustransforms，increaseswiththeproductivenessofhislabour。Butthosemeansofproductionplayadoublepart。Theincreaseofsomeisaconsequence，thatoftheothersaconditionoftheincreasingproductivityoflabour。E。g。，withthedivisionoflabourinmanufacture，andwiththeuseofmachinery，morerawmaterialisworkedupinthesametime，and，therefore，agreatermassofrawmaterialandauxiliarysubstancesenterintothelabour—process。
　　Thatistheconsequenceoftheincreasingproductivityoflabour。Ontheotherhand，themassofmachinery，beastsofburden，mineralmanures，drain—pipes，&c。，isaconditionoftheincreasingproductivityoflabour。Soalsoisitwiththemeansofproductionconcentratedinbuildings，furnaces，meansoftransport，&c。Butwhetherconditionorconsequence，thegrowingextentofthemeansofproduction，ascomparedwiththelabour—powerincorporatedwiththem，isanexpressionofthegrowingproductivenessoflabour。Theincreaseofthelatterappears，therefore，inthediminutionofthemassoflabourinproportiontothemassofmeansofproductionmovedbyit，orinthediminutionofthesubjectivefactorofthelabour—processascomparedwiththeobjectivefactor。
　　Thischangeinthetechnicalcompositionofcapital，thisgrowthinthemassofmeansofproduction，ascomparedwiththemassofthelabour—powerthatvivifiesthem，isreflectedagaininitsvalue—composition，bytheincreaseoftheconstantconstituentofcapitalattheexpenseofitsvariableconstituent。Theremaybe，e。g。，originally50percent。ofacapitallaidoutinmeansofproduction，and50percent。inlabour—power;lateron，withthedevelopmentoftheproductivityoflabour，80percent。inmeansofproduction，20percent。inlabour—power，andsoon。Thislawoftheprogressiveincreaseinconstantcapital，inproportiontothevariable，isconfirmedateverystep（asalreadyshown）bythecomparativeanalysisofthepricesofcommodities，whetherwecomparedifferenteconomicepochsordifferentnationsinthesameepoch。Therelativemagnitudeoftheelementofprice，whichrepresentsthevalueofthemeansofproductiononly，ortheconstantpartofcapitalconsumed，isindirect，therelativemagnitudeoftheotherelementofpricethatpayslabour（thevariablepartofcapital）
　　isininverseproportiontotheadvanceofaccumulation。
　　Thisdiminutioninthevariablepartofcapitalascomparedwiththeconstant，orthealteredvalue—compositionofthecapital，however，onlyshowsapproximatelythechangeinthecompositionofitsmaterialconstituents。
　　If，e。g。，thecapital—valueemployedto—dayinspinningis7/8constantand1/8variable，whilstatthebeginningofthe18thcenturyitwas1/2
　　constantand1/2variable，ontheotherhand，themassofrawmaterial，instrumentsoflabour，&c。，thatacertainquantityofspinninglabourconsumesproductivelyto—day，ismanyhundredtimesgreaterthanatthebeginningofthe18thcentury。Thereasonissimplythat，withtheincreasingproductivityoflabour，notonlydoesthemassofthemeansofproductionconsumedbyitincrease，buttheirvaluecomparedwiththeirmassdiminishes。
　　Theirvaluethereforerisesabsolutely，butnotinproportiontotheirmass。Theincreaseofthedifferencebetweenconstantandvariablecapital，is，therefore，muchlessthanthatofthedifferencebetweenthemassofthemeansofproductionintowhichtheconstant，andthemassofthelabour—powerintowhichthevariable，capitalisconverted。Theformerdifferenceincreaseswiththelatter，butinasmallerdegree。
　　But，iftheprogressofaccumulationlessenstherelativemagnitudeofthevariablepartofcapital，itbynomeans，indoingthis，excludesthepossibilityofariseinitsabsolutemagnitude。Supposethatacapital—valueatfirstisdividedinto50percent。ofconstantand50percent。ofvariablecapital;laterinto80percent。ofconstantand20percent。ofvariable。
　　Ifinthemeantimetheoriginalcapital，say£6，000，hasincreasedto£18，000，itsvariableconstituenthasalsoincreased。Itwas£3，000，itisnow£3，600。Butwhereasformerlyanincreaseofcapitalby20percent。wouldhavesufficedtoraisethedemandforlabour20percent。，nowthislatterriserequiresatriplingoftheoriginalcapital。
　　InPartIV。itwasshown，howthedevelopmentoftheproductivenessofsociallabourpre—supposesco—operationonalargescale;howitisonlyuponthissuppositionthatdivisionandcombinationoflabourcanbeorganised，andthemeansofproductioneconomisedbyconcentrationonavastscale;howinstrumentsoflabourwhich，fromtheirverynature，areonlyfitforuseincommon，suchasasystemofmachinery，canbecalledintobeing;howhugenaturalforcescanbepressedintotheserviceofproduction;andhowthetransformationcanbeeffectedoftheprocessofproductionintoatechnologicalapplicationofscience。Onthebasisoftheproductionofcommodities，wherethemeansofproductionarethepropertyofprivatepersons，andwheretheartisanthereforeeitherproducescommodities，isolatedfromandindependentofothers，orsellshislabour—powerasacommodity，becausehelacksthemeansforindependentindustry，co—operationonalargescalecanrealiseitselfonlyintheincreaseofindividualcapitals，onlyinproportionasthe—meansofsocialproductionandthemeansofsubsistencearetransformedintotheprivatepropertyofcapitalists。
　　Thebasisoftheproductionofcommoditiescanadmitofproductiononalargescaleinthecapitalisticformalone。Acertainaccumulationofcapital，inthehandsofindividualproducersofcommodities，formsthereforethenecessarypreliminaryofthespecificallycapitalisticmodeofproduction。
　　Wehad，therefore，toassumethatthisoccursduringthetransitionfromhandicrafttocapitalisticindustry。Itmaybecalledprimitiveaccumulation，becauseitisthehistoricbasis，insteadofthehistoricresultofspecificallycapitalistproduction。Howititselforiginates，weneednothereinquireasyet。Itisenoughthatitformsthestarting—point。Butallmethodsforraisingthesocialproductivepoweroflabourthataredevelopedonthisbasis，areatthesametimemethodsfortheincreasedproductionofsurplus—valueorsurplus—product，whichinitsturnistheformativeelementofaccumulation。Theyare，therefore，atthesametimemethodsoftheproductionofcapitalbycapital，ormethodsofitsacceleratedaccumulation。Thecontinualre—transformationofsurplus—valueintocapitalnowappearsintheshapeoftheincreasingmagnitudeofthecapitalthatentersintotheprocessofproduction。Thisinturnisthebasisofanextendedscaleofproduction，ofthemethodsforraisingtheproductivepoweroflabourthataccompanyit，andofacceleratedproductionofsurplus—value。If，therefore，acertaindegreeofaccumulationofcapitalappearsasaconditionofthespecificallycapitalistmodeofproduction，thelattercausesconverselyanacceleratedaccumulationofcapital。Withtheaccumulationofcapital，therefore，thespecificallycapitalisticmodeofproductiondevelops，andwiththecapitalistmodeofproductiontheaccumulationofcapital。Boththeseeconomicfactorsbringabout，inthecompoundratiooftheimpulsestheyreciprocallygiveoneanother，thatchangeinthetechnicalcompositionofcapitalbywhichthevariableconstituentbecomesalwayssmallerandsmallerascomparedwiththeconstant。
　　Everyindividualcapitalisalargerorsmallerconcentrationofmeansofproduction，withacorrespondingcommandoveralargerorsmallerlabour—army。
　　Everyaccumulationbecomesthemeansofnewaccumulation。Withtheincreasingmassofwealthwhichfunctionsascapital，accumulationincreasestheconcentrationofthatwealthinthehandsofindividualcapitalists，andtherebywidensthebasisofproductiononalargescaleandofthespecificmethodsofcapitalistproduction。Thegrowthofsocialcapitaliseffectedbythegrowthofmanyindividualcapitals。Allothercircumstancesremainingthesame，individualcapitals，andwiththemtheconcentrationofthemeansofproduction，increaseinsuchproportionastheyformaliquotpartsofthetotalsocialcapital。Atthesametimeportionsoftheoriginalcapitalsdisengagethemselvesandfunctionasnewindependentcapitals。
　　Besidesothercauses，thedivisionofproperty，withincapitalistfamilies，playsagreatpartinthis。Withtheaccumulationofcapital，therefore，thenumberofcapitalistsgrowstoagreaterorlessextent。Twopointscharacterisethiskindofconcentrationwhichgrowsdirectlyoutof，orratherisidenticalwith，accumulation。First:Theincreasingconcentrationofthesocialmeansofproductioninthehandsofindividualcapitalistsis，otherthingsremainingequal，limitedbythedegreeofincreaseofsocialwealth。Second:Thepartofsocialcapitaldomiciledineachparticularsphereofproductionisdividedamongmanycapitalistswhofaceoneanotherasindependentcommodity—producerscompetingwitheachother。Accumulationandtheconcentrationaccompanyingitare，therefore，notonlyscatteredovermanypoints，buttheincreaseofeachfunctioningcapitalisthwartedbytheformationofnewandthesub—divisionofoldcapitals。Accumulation，therefore，presentsitselfontheonehandasincreasingconcentrationofthemeansofproduction，andofthecommandoverlabour;ontheother，asrepulsionofmanyindividualcapitalsonefromanother。
　　Thissplitting—upofthetotalsocialcapitalintomanyindividualcapitalsortherepulsionofitsfractionsonefromanother，iscounteractedbytheirattraction。Thislastdoesnotmeanthatsimpleconcentrationofthemeansofproductionandofthecommandoverlabour，whichisidenticalwithaccumulation。Itisconcentrationofcapitalsalreadyformed，destructionoftheirindividualindependence，expropriationofcapitalistbycapitalist，transformationofmanysmallintofewlargecapitals。Thisprocessdiffersfromtheformerinthis，thatitonlypre—supposesachangeinthedistributionofcapitalalreadytohand，andfunctioning;itsfieldofactionisthereforenotlimitedbytheabsolutegrowthofsocialwealth，bytheabsolutelimitsofaccumulation。Capitalgrowsinoneplacetoahugemassinasinglehand，becauseithasinanotherplacebeenlostbymany。Thisiscentralisationproper，asdistinctfromaccumulationandconcentration。
　　Thelawsofthiscentralisationofcapitals，oroftheattractionofcapitalbycapital，cannotbedevelopedhere。Abriefhintatafewfactsmustsuffice。Thebattleofcompetitionisfoughtbycheapeningofcommodities。
　　Thecheapnessofcommoditiesdemands，caeterisparibus，ontheproductivenessoflabour，andthisagainonthescaleofproduction。Therefore，thelargercapitalsbeatthesmaller。Itwillfurtherberememberedthat，withthedevelopmentofthecapitalistmodeofproduction，thereisanincreaseintheminimumamountofindividualcapitalnecessarytocarryonabusinessunderitsnormalconditions。Thesmallercapitals，therefore，crowdintospheresofproductionwhichModernIndustryhasonlysporadicallyorincompletelygotholdof。Herecompetitionragesindirectproportiontothenumber，andininverseproportiontothemagnitudes，oftheantagonisticcapitals。Italwaysendsintheruinofmanysmallcapitalists，whosecapitalspartlypassintothehandsoftheirconquerors，partlyvanish。Apartfromthis，withcapitalistproductionanaltogethernewforcecomesintoplay？thecreditsystem，whic;[11]initsfirststagesfurtivelycreepsinasthehumbleassistantofaccumulation，drawingintothehandsofindividualorassociatedcapitalists，byinvisiblethreads，themoneyresourceswhichliescattered，overthesurfaceofsociety，inlargerorsmalleramounts;butitsoonbecomesanewandterribleweaponinthebattleofcompetitionandisfinallytransformedintoanenormoussocialmechanismforthecentralisationofcapitals。
　　Commensuratelywiththedevelopmentofcapitalistproductionandaccumulationtheredevelopthetwomostpowerfulleversofcentralisation？competitionandcredit。Atthesametimetheprogressofaccumulationincreasesthematerialamenabletocentralisation，i。e。，theindividualcapitals，whilsttheexpansionofcapitalistproductioncreates，ontheonehand，thesocialwant，and，ontheother，thetechnicalmeansnecessaryforthoseimmenseindustrialundertakingswhichrequireapreviouscentralisationofcapitalfortheiraccomplishment。To—day，therefore，theforceofattraction，drawingtogetherindividualcapitals，andthetendencytocentralisationarestrongerthaneverbefore。Butiftherelativeextensionandenergyofthemovementtowardscentralisationisdetermined，inacertaindegree，bythemagnitudeofcapitalistwealthandsuperiorityofeconomicmechanismalreadyattained，progressincentralisationdoesnotinanywaydependuponapositivegrowthinthemagnitudeofsocialcapital。Andthisisthespecificdifferencebetweencentralisationandconcentration，thelatterbeingonlyanothernameforreproductiononanextendedscale。
　　Centralisationmayresultfromamerechangeinthedistributionofcapitalsalreadyexisting，fromasimplealterationinthequantitativegroupingofthecomponentpartsofsocialcapital。Herecapitalcangrowintopowerfulmassesinasinglehandbecausethereithasbeenwithdrawnfrommanyindividualhands。Inanygivenbranchofindustrycentralisationwouldreachitsextremelimitifalltheindividualcapitalsinvestedinitwerefusedintoasinglecapital。[12]Ina，givensocietythelimitwouldbereachedonlywhentheentiresocialcapitalwasunitedinthehandsofeitherasinglecapitalistorasinglecapitalistcompany。
　　Centralisationcompletestheworkofaccumulationbyenablingindustrialcapitaliststoextendthescaleoftheiroperations。Whetherthislatterresultistheconsequenceofaccumulationorcentralisation，whethercentralisationisaccomplishedbytheviolentmethodofannexation？whencertaincapitalsbecomesuchpreponderantcentresofattractionforothersthattheyshattertheindividualcohesionofthelatterandthendrawtheseparatefragmentstothemselves？orwhetherthefusionofanumberofcapitalsalreadyformedorinprocessofformationtakesplacebythesmootherprocessoforganisingjoint—stockcompanies？theeconomiceffectremainsthesame。Everywheretheincreasedscaleofindustrialestablishmentsisthestarting—pointforamorecomprehensiveorganisationofthecollectiveworkofmany，forawiderdevelopmentoftheirmaterialmotiveforces？inotherwords，fortheprogressivetransformationofisolatedprocessesofproduction，carriedonbycustomarymethods，intoprocessesofproductionsociallycombinedandscientificallyarranged。
　　Butaccumulation，thegradualincreaseofcapitalbyreproductionasitpassesfromthecirculartothespiralform，isclearlyaveryslowprocedurecomparedwithcentralisation，whichhasonlytochangethequantitativegroupingsoftheconstituentpartsofsocialcapital。Theworldwouldstillbewithoutrailwaysifithadhadtowaituntilaccumulationhadgotafewindividualcapitalsfarenoughtobeadequatefortheconstructionofarailway。Centralisation，onthecontrary，accomplishedthisinthetwinklingofaneye，bymeansofjoint—stockcompanies。Andwhilstcentralisationthusintensifiesandacceleratestheeffectsofaccumulation，itsimultaneouslyextendsandspeedsthoserevolutionsinthetechnicalcompositionofcapitalwhichraiseitsconstantportionattheexpenseofitsvariableportion，thusdiminishingtherelativedemandforlabour。
　　Themassesofcapitalfusedtogetherovernightbycentralisationreproduceandmultiplyastheothersdo，onlymorerapidly，therebybecomingnewandpowerfulleversinsocialaccumulation。Therefore，whenwespeakoftheprogressofsocialaccumulationwetacitlyinclude？to—day？theeffectsofcentralisation。
　　Theadditionalcapitalsformedinthenormalcourseofaccumulation（seeChapterXXIV，Section1）serveparticularlyasvehiclesfortheexploitationofnewinventionsanddiscoveries，andindustrialimprovementsingeneral。
　　Butintimetheoldcapitalalsoreachesthemomentofrenewalfromtoptotoe，whenitshedsitsskinandisrebornliketheothersinaperfectedtechnicalform，inwhichasmallerquantityoflabourwillsufficetosetinmotionalargerquantityofmachineryandrawmaterials。Theabsolutereductioninthedemandforlabourwhichnecessarilyfollowsfromthisisobviouslysomuchthegreaterthehigherthedegreeinwhichthecapitalsundergoingthisprocessofrenewalarealreadymassedtogetherbyvirtueofthecentralisationmovement。
　　Ontheonehand，therefore，theadditionalcapitalformedinthecourseofaccumulationattractsfewerandfewerlabourersinproportiontoitsmagnitude。Ontheotherhand，theoldcapitalperiodicallyreproducedwithchangeofcomposition，repelsmoreandmoreofthelabourersformerlyemployedbyit。
　　SECTION3。PROGRESSIVEPRODUCTIONOFARELATIVESURPLUS—POPULATIONORINDUSTRIALRESERVE
　　ARMY
　　Theaccumulationofcapital，thoughoriginallyappearingasitsquantitativeextensiononly，iseffected，aswehaveseen，underaprogressivequalitativechangeinitscomposition，underaconstantincreaseofitsconstant，attheexpenseofitsvariableconstituent。[13]
　　Thespecificallycapitalistmodeofproduction，thedevelopmentoftheproductivepoweroflabourcorrespondingtoit，andthechangethenceresultingintheorganiccompositionofcapital，donotmerelykeeppacewiththeadvanceofaccumulation，orwiththegrowthofsocialwealth。Theydevelopatamuchquickerrate，becausemereaccumulation，theabsoluteincreaseofthetotalsocialcapital，isaccompaniedbythecentralisationoftheindividualcapitalsofwhichthattotalismadeup;andbecausethechangeinthetechnologicalcompositionoftheadditionalcapitalgoeshandinhandwithasimilarchangeinthetechnologicalcompositionoftheoriginalcapital。Withtheadvanceofaccumulation，therefore，theproportionofconstanttovariablecapitalchanges。Ifitwasoriginallysay1:1，itnowbecomessuccessively2:1，3:1，4:1，5:1，7:1，&c。，sothat，asthecapitalincreases，insteadof1/2ofitstotalvalue，only1/3，1/4，1/5，1/6，1/8，&c。，istransformedintolabour—power，and，ontheotherhand，2/3，3/4，4/5，5/6，7/8intomeansofproduction。
　　Sincethedemandforlabourisdeterminednotbytheamountofcapitalasawhole，butbyitsvariableconstituentalone，thatdemandfallsprogressivelywiththeincreaseofthetotalcapital，insteadof，aspreviouslyassumed，risinginproportiontoit。Itfallsrelativelytothemagnitudeofthetotalcapital，andatanacceleratedrate，asthismagnitudeincreases。
　　Withthegrowthofthetotalcapital，itsvariableconstituentorthelabourincorporatedinit，alsodoesincrease，butinaconstantlydiminishingproportion。Theintermediatepausesareshortened，inwhichaccumulationworksassimpleextensionofproduction，onagiventechnicalbasis。Itisnotmerelythatanacceleratedaccumulationoftotalcapital，acceleratedinaconstantlygrowingprogression，isneededtoabsorbanadditionalnumberoflabourers，oreven，onaccountoftheconstantmetamorphosisofoldcapital，tokeepemployedthosealreadyfunctioning。Initsturn，thisincreasingaccumulationandcentralisationbecomesasourceofnewchangesinthecompositionofcapital，ofamoreaccelerateddiminutionofitsvariable，ascomparedwithitsconstantconstituent。Thisacceleratedrelativediminutionofthevariableconstituent，thatgoesalongwiththeacceleratedincreaseofthetotalcapital，andmovesmorerapidlythanthisincrease，takestheinverseform，attheotherpole，ofanapparentlyabsoluteincreaseofthelabouringpopulation，anincreasealwaysmovingmorerapidlythanthatofthevariablecapitalorthemeansofemployment。
　　Butinfact，itiscapitalisticaccumulationitselfthatconstantlyproduces，andproducesinthedirectratioofitsownenergyandextent，arelativityredundantpopulationoflabourers，i。e。，apopulationofgreaterextentthansufficesfortheaverageneedsoftheself—expansionofcapital，andthereforeasurplus—population。
　　Consideringthesocialcapitalinitstotality，themovementofitsaccumulationnowcausesperiodicalchanges，affectingitmoreorlessasawhole，nowdistributesitsvariousphasessimultaneouslyoverthedifferentspheresofproduction。Insomespheresachangeinthecompositionofcapitaloccurswithoutincreaseofitsabsolutemagnitude，asaconsequenceofsimplecentralisation;inotherstheabsolutegrowthofcapitalisconnectedwithabsolutediminutionofitsvariableconstituent，orofthelabour—powerabsorbedbyit;inothersagain，capitalcontinuesgrowingforatimeonitsgiventechnicalbasis，andattractsadditionallabour—powerinproportiontoitsincrease，whileatothertimesitundergoesorganicchange，andlessensitsvariableconstituent;inallspheres，theincreaseofthevariablepartofcapital，andthereforeofthenumberoflabourersemployedbyit，isalwaysconnectedwithviolentfluctuationsandtransitoryproductionofsurplus—population，whetherthistakesthemorestrikingformoftherepulsionoflabourersalreadyemployed，orthelessevidentbutnotlessrealformofthemoredifficultabsorptionoftheadditionallabouringpopulationthroughtheusualchannels。[14]Withthemagnitudeofsocialcapitalalreadyfunctioning，andthedegreeofitsincrease，withtheextensionofthescaleofproduction，andthemassofthelabourerssetinmotion，withthedevelopmentoftheproductivenessoftheirlabour，withthegreaterbreadthandfulnessofallsourcesofwealth，thereisalsoanextensionofthescaleonwhichgreaterattractionoflabourersbycapitalisaccompaniedbytheirgreaterrepulsion;therapidityofthechangeintheorganiccompositionofcapital，andinitstechnicalformincreases，andanincreasingnumberofspheresofproductionbecomesinvolvedinthischange，nowsimultaneously，nowalternately。
　　Thelabouringpopulationthereforeproduces，alongwiththeaccumulationofcapitalproducedbyit，themeansbywhichititselfismaderelativelysuperfluous，isturnedintoarelativesurplus—population;anditdoesthistoanalwaysincreasingextent。[15]Thisisalawofpopulationpeculiartothecapitalistmodeofproduction;
　　andinfacteveryspecialhistoricmodeofproductionhasitsownspeciallawsofpopulation，historicallyvalidwithinitslimitsandonlyinsofarasmanhasnotinterferedwiththem。
　　Butifasurpluslabouringpopulationisanecessaryproductofaccumulationorofthedevelopmentofwealthonacapitalistbasis，thissurplus—populationbecomes，conversely，theleverofcapitalisticaccumulation，nay，aconditionofexistenceofthecapitalistmodeofproduction。Itformsadisposableindustrialreservearmy，thatbelongstocapitalquiteasabsolutelyasifthelatterhadbreditatitsowncost。Independentlyofthelimitsoftheactualincreaseofpopulation，itcreates，forthechangingneedsoftheself—expansionofcapital，amassofhumanmaterialalwaysreadyforexploitation。Withaccumulation，andthedevelopmentoftheproductivenessoflabourthataccompaniesit，thepowerofsuddenexpansionofcapitalgrowsalso;itgrows，notmerelybecausetheelasticityofthecapitalalreadyfunctioningincreases，notmerelybecausetheabsolutewealthofsocietyexpands，ofwhichcapitalonlyformsanelasticpart，notmerelybecausecredit，undereveryspecialstimulus，atonceplacesanunusualpartofthiswealthatthedisposalofproductionintheformofadditionalcapital;itgrows，also，becausethetechnicalconditionsoftheprocessofproductionthemselves？machinery，meansoftransport，&c。？nowadmitoftherapidesttransformationofmassesofsurplus—productintoadditionalmeansofproduction。Themassofsocialwealth，overflowingwiththeadvanceofaccumulation，andtransformableintoadditionalcapital，thrustsitselffranticallyintooldbranchesofproduction，whosemarketsuddenlyexpands，orintonewlyformedbranches，suchasrailways，&c。，theneedforwhichgrowsoutofthedevelopmentoftheoldones。Inallsuchcases，theremustbethepossibilityofthrowinggreatmassesofmensuddenlyonthedecisivepointswithoutinjurytothescaleofproductioninotherspheres。Overpopulationsuppliesthesemasses。Thecourp;characteristicofmodernindustry，viz。，adecennialcycle（interruptedbysmalleroscillations），ofperiodsofaverageactivity，productionathighpressure，crisisandstagnation，dependsontheconstantformation，thegreaterorlessabsorption，andthere—formationoftheindustrialreservearmyorsurplus—population。Intheirturn，thevaryingphasesoftheindustrialcyclerecruitthesurplus—population，andbecomeoneofthemostenergeticagentsofitsreproduction。Thispeculiarcourseofmodemindustry，whichoccursinnoearlierperiodofhumanhistory，wasalsoimpossibleinthechildhoodofcapitalistproduction。Thecompositionofcapitalchangedbutveryslowly。Withitsaccumulation，therefore，therekeptpace，onthewhole，acorrespondinggrowthinthedemandforlabour。Slowaswastheadvanceofaccumulationcomparedwiththatofmoremodemtimes，itfoundacheckinthenaturallimitsoftheexploitablelabouringpopulation，limitswhichcouldonlybegotridofbyforciblemeanstobementionedlater。Theexpansionbyfitsandstartsofthescaleofproductionisthepreliminarytoitsequallysuddencontraction;thelatteragainevokestheformer，buttheformerisimpossiblewithoutdisposablehumanmaterial，withoutanincrease，inthenumberoflabourersindependentlyoftheabsolutegrowthofthepopulation。Thisincreaseiseffectedbythesimpleprocessthatconstantly"setsfree"apartofthelabourers;bymethodswhichlessenthenumberoflabourersemployedinproportiontotheincreasedproduction。
　　Thewholeformofthemovementofmodemindustrydepends，therefore，upontheconstanttransformationofapartofthelabouringpopulationintounemployedorhalf—employedhands。ThesuperficialityofPoliticalEconomyshowsitselfinthefactthatitlooksupontheexpansionandcontractionofcredit，whichisameresymptomoftheperiodicchangesoftheindustrialcycle，astheircause。Astheheavenlybodies，oncethrownintoacertaindefinitemotion，alwaysrepeatthis，soisitwithsocialproductionassoonasitisoncethrownintothismovementofalternateexpansionandcontraction。Effects，intheirturn，becomecauses，andthevaryingaccidentsofthewholeprocess，whichalwaysreproducesitsownconditions，takeontheformofperiodicity。Whenthisperiodicityisonceconsolidated，evenPoliticalEconomythenseesthattheproductionofarelativesurplus—population？i。e。，surpluswithregardtotheaverageneedsoftheself—expansionofcapital？isanecessaryconditionofmodernindustry。
　　"Suppose，"saysH。Merivale，formerlyProfessorofPoliticalEconomyatOxford，subsequentlyemployedintheEnglishColonialOffice，"supposethat，ontheoccasionofsomeofthesecrises，thenationweretorouseitselftotheeffortofgettingridbyemigrationofsomehundredsofthousandsofsuperfluousarms，whatwouldbetheconsequence？That，atthefirstreturningdemandforlabour，therewouldbeadeficiency。
　　Howeverrapidreproductionmaybe，ittakes，atallevents，thespaceofagenerationtoreplacethelossofadultlabour。Now，theprofitsofourmanufacturersdependmainlyonthepowerofmaking’useoftheprosperousmomentwhendemandisbrisk，andthuscompensatingthemselvesfortheintervalduringwhichitisslack。Thispowerissecuredtothemonlybythecommandofmachineryandofmanuallabour。Theymusthavehandsreadybythem，theymustbeabletoincreasetheactivityoftheiroperationswhenrequired，andtoslackenitagain，accordingtothestateofthemarket，ortheycannotpossiblymaintainthatpre—eminenceintheraceofcompetitiononwhichthewealthofthecountryisfounded。"[16]EvenMalthusrecognisesoverpopulationasanecessityofmodemindustry，though，afterhisnarrowfashion，heexplainsitbytheabsoluteover—growthofthelabouringpopulation，notbytheirbecomingrelativelysupernumerary。
　　Hesays:"Prudentialhabitswithregardtomarriage，carriedtoaconsiderableextentamongthelabouringclassofacountrymainlydependinguponmanufacturesandcommerce，mightinjureit……Fromthenatureofapopulation，anincreaseoflabourerscannotbebroughtintomarketinconsequenceofaparticulardemandtillafterthelapseof16or18years，andtheconversionofrevenueintocapital，bysaving，maytakeplacemuchmorerapidly:acountryisalwaysliabletoanincreaseinthequantityofthefundsforthemaintenanceoflabourfasterthantheincreaseofpopulation。"[17]AfterPoliticalEconomyhasthusdemonstratedtheconstantproductionofarelativesurplus—populationoflabourerstobeanecessityofcapitalisticaccumulation，sheveryaptly，intheguiseofanoldmaid，putsinthemouthofher"beauideal"ofacapitalistthefollowingwordsaddressedtothosesupernumerariesthrownonthestreetsbytheirowncreationofadditionalcapital:？"Wemanufacturersdowhatwecanforyou，whilstweareincreasingthatcapitalonwhichyoumustsubsist，andyoumustdotherestbyaccommodatingyournumberstothemeansofsubsistence。;[18]
　　Capitalistproductioncanbynomeanscontentitselfwiththequantityofdisposablelabour—powerwhichthenaturalincreaseofpopulationyields。
　　Itrequiresforitsfreeplayanindustrialreservearmyindependentofthesenaturallimits。
　　Uptothispointithasbeenassumedthattheincreaseordiminutionofthevariablecapitalcorrespondsrigidlywiththeincreaseordiminutionofthenumberoflabourersemployed。
　　Thenumberoflabourerscommandedbycapitalmayremainthesame，orevenfall，whilethevariablecapitalincreases。Thisisthecaseiftheindividuallaboureryieldsmorelabour，andthereforehiswagesincrease，andthisalthoughthepriceoflabourremainsthesameorevenfalls，onlymoreslowlythanthemassoflabourrises。Increaseofvariablecapital，inthiscase，becomesanindexofmorelabour，butnotofmorelabourersemployed。Itistheabsoluteinterestofeverycapitalisttopressagivenquantityoflabouroutofasmaller，ratherthanagreaternumberoflabourers，ifthecostisaboutthesame。Inthelattercase，theoutlayofconstantcapitalincreasesinproportiontothemassoflaboursetinaction;intheformerthatincreaseismuchsmaller。Themoreextendedthescaleofproduction，thestrongerthismotive。Itsforceincreaseswiththeaccumulationofcapital。
　　Wehaveseenthatthedevelopmentofthecapitalistmodeofproductionandoftheproductivepoweroflabour？atoncethecauseandeffectofaccumulation？enablesthecapitalist，withthesameoutlayofvariablecapital，tosetinactionmorelabourbygreaterexploitation（extensiveorintensive）ofeachindividuallabour—power。Wehavefurtherseenthatthecapitalistbuyswiththesamecapitalagreatermassoflabour—power，asheprogressivelyreplacesskilledlabourersbylessskilled，maturelabour—powerbyimmature，malebyfemale，thatofadultsbythatofyoungpersonsorchildren。
　　Ontheonehand，therefore，withtheprogressofaccumulation，alargervariablecapitalsetsmorelabourinactionwithoutenlistingmorelabourers;
　　ontheother，avariablecapitalofthesamemagnitudesetsinactionmorelabourwiththesamemassoflabour—power;and，finally，agreaternumberofinferiorlabour—powersbydisplacementofhigher。
　　Theproductionofarelativesurplus—population，orthesettingfreeoflabourers，goesonthereforeyetmorerapidlythanthetechnicalrevolutionoftheprocessofproductionthataccompanies，andisacceleratedby，theadvanceofaccumulation;andmorerapidlythanthecorrespondingdiminutionofthevariablepartofcapitalascomparedwiththeconstant。Ifthemeansofproduction，astheyincreaseinextentandeffectivepower，becometoalessextentmeansofemploymentoflabourers，thisstateofthingsisagainmodifiedbythefactthatinproportionastheproductivenessoflabourincreases，capitalincreasesitssupplyoflabourmorequicklythanitsdemandforlabourers。Theover—workoftheemployedpartoftheworking—classswellstheranksofthereserve，whilstconverselythegreaterpressurethatthelatterbyitscompetitionexertsontheformer，forcesthesetosubmittooverworkandtosubjugationunderthedictatesofcapital。Thecondemnationofonepartoftheworking—classtoenforcedidlenessbytheoverworkoftheotherpart，andtheconverse，becomesameansofenrichingtheindividualcapitalists，[19]andacceleratesatthesametimetheproductionoftheindustrialreservearmyonascalecorrespondingwiththeadvanceofsocialaccumulation。
　　Howimportantisthiselementintheformationoftherelativesurplus—population，isshownbytheexampleofEngland。Hertechnicalmeansforsavinglabourarecolossal。Nevertheless，ifto—morrowmorninglabourgenerallywerereducedtoarationalamount，andproportionedtothedifferentsectionsoftheworking—classaccordingtoageandsex，theworkingpopulationtohandwouldbeabsolutelyinsufficientforthecarryingonofnationalproductiononitspresentscale。Thegreatmajorityofthelabourersnow"unproductive"