Theartofwar，however，asitiscertainlythenoblestofallarts，sointheprogressofimprovementitnecessarilybecomesoneofthemostcomplicatedamongthem。Thestateofthemechanical，aswellasofsomeotherarts，withwhichitisnecessarilyconnected，determinesthedegreeofperfectiontowhichitiscapableofbeingcarriedatanyparticulartime。Butinordertocarryittothisdegreeofperfection，itisnecessarythatitshouldbecomethesoleorprincipaloccupationofaparticularclassofcitizens，andthedivisionoflabourisasnecessaryfortheimprovementofthis，asofeveryotherart。
Intootherartsthedivisionoflabourisnaturallyintroducedbytheprudenceofindividuals，whofindthattheypromotetheirprivateinterestbetterbyconfiningthemselvestoaparticulartradethanbyexercisingagreatnumber。Butitisthewisdomofthestateonlywhichcanrenderthetradeofasoldieraparticulartradeseparateanddistinctfromallothers。Aprivatecitizenwho，intimeofprofoundpeace，andwithoutanyparticularencouragementfromthepublic，shouldspendthegreaterpartofhistimeinmilitaryexercises，might，nodoubt，bothimprovehimselfverymuchinthem，andamusehimselfverywell;buthecertainlywouldnotpromotehisowninterest。Itisthewisdomofthestateonlywhichcanrenderitforhisinteresttogiveupthegreaterpartofhistimetothispeculiaroccupation:andstateshavenotalwayshadthiswisdom，evenwhentheircircumstanceshadbecomesuchthatthepreservationoftheirexistencerequiredthattheyshouldhaveit。
Ashepherdhasagreatdealofleisure;ahusbandman，intherudestateofhusbandry，hassome;anartificerormanufacturerhasnoneatall。Thefirstmay，withoutanyloss，employagreatdealofhistimeinmartialexercises;thesecondmayemploysomepartofit;butthelastcannotemployasinglehourinthemwithoutsomeloss，andhisattentiontohisowninterestnaturallyleadshimtoneglectthemaltogether。Theseimprovementsinhusbandrytoo，whichtheprogressofartsandmanufacturesnecessarilyintroduces，leavethehusbandmanaslittleleisureastheartificer。Militaryexercisescometobeasmuchneglectedbytheinhabitantsofthecountryasbythoseofthetown，andthegreatbodyofthepeoplebecomesaltogetherunwarlike。Thatwealth，atthesametime，whichalwaysfollowstheimprovementsofagricultureandmanufactures，andwhichinrealityisnomorethantheaccumulatedproduceofthoseimprovements，provokestheinvasionofalltheirneighbours。Anindustrious，anduponthataccountawealthynation，isofallnationsthemostlikelytobeattacked;andunlessthestatetakessomenewmeasuresforthepublicdefence，thenaturalhabitsofthepeoplerenderthemaltogetherincapableofdefendingthemselves。
Inthesecircumstancesthereseemtobebuttwomethodsbywhichthestatecanmakeanytolerableprovisionforthepublicdefence。
Itmayeither，first，bymeansofaveryrigorouspolice，andinspiteofthewholebentoftheinterest，genius，andinclinationsofthepeople，enforcethepracticeofmilitaryexercises，andobligeeitherallthecitizensofthemilitaryage，oracertainnumberofthem，tojoininsomemeasurethetradeofasoldiertowhateverothertradeorprofessiontheymayhappentocarryon。