Insofarastheeconomicalconditionofnationsturnsuponthestateofphysicalknowledge，itisasubjectforthephysicalsciences，andtheartsfoundedonthem。Butinsofarasthecausesaremoralorpsychological，dependentoninstitutionsandsocialrelations，orontheprinciplesofhumannature，theirinvestigationbelongsnottophysical，buttomoralandsocialscience，andistheobjectofwhatiscalledPoliticalEconomy。
Theproductionofwealth;theextractionoftheinstrumentsofhumansubsistenceandenjoymentfromthematerialsoftheglobe，isevidentlynotanarbitrarything。Ithasitsnecessaryconditions。Ofthese，somearephysical，dependingonthepropertiesofmatter，andontheamountofknowledgeofthosepropertiespossessedattheparticularplaceandtime。ThesePoliticalEconomydoesnotinvestigate，butassumes;referringforthegrounds，tophysicalscienceorcommonexperience。
Combiningwiththesefactsofoutwardnatureothertruthsrelatingtohumannature，itattemptstotracethesecondaryorderivativelaws，bywhichtheproductionofwealthisdetermined;
inwhichmustlietheexplanationofthediversitiesofrichesandpovertyinthepresentandpast，andthegroundofwhateverincreaseinwealthisreservedforthefuture。
UnlikethelawsofProduction，thoseofDistributionarepartlyofhumaninstitution:sincethemannerinwhichwealthisdistributedinanygivensociety，dependsonthestatutesorusagesthereinobtaining。Butthoughgovernmentsornationshavethepowerofdecidingwhatinstitutionsshallexist，theycannotarbitrarilydeterminehowthoseinstitutionsshallwork。Theconditionsonwhichthepowertheypossessoverthedistributionofwealthisdependent，andthemannerinwhichthedistributioniseffectedbythevariousmodesofconductwhichsocietymaythinkfittoadopt，areasmuchasubjectforscientificenquiryasanyofthephysicallawsofnature。