Whyanotherbookonquantumfieldtheory?Todaythestudentofquantumfieldtheorycanchoosefromamongascoreofexcellentbooks,severalofthemquiteup-to-date.Anotherbookwillbeworthwhileonlyifitofferssomethingnewincontentorperspective.
Astocontent,althoughthisbookcontainsagoodamountofnewmaterial,Isupposethemostdistinctivethingaboutitisitsgenerality;Ihavetriedthroughouttodiscussmattersinacontextthatisasgeneralaspossible.Thisisinpartbecausequantumfieldtheoryhasfoundapplicationsfarremovedfromthesceneofitsoldsuccesses,quantumelectrodynamics,butevenmorebecauseIthinkthatthisgeneralitywillhelptokeeptheimportantpointsfrombeingsubmergedinthetechnicalitiesofspecifictheories.Ofcourse,specificexamplesarefrequentlyusedtoillustrategeneralpoints,examplesthatarechosenfromcontemporaryparticlephysicsornuclearphysicsaswellasfromquantumelectrodynamics.
Itis,however,theperspectiveofthisbook,ratherthanitscontent,thatprovidedmychiefmotivationinwritingit.Iaimtopresentquantumfieldtheoryinamannerthatwillgivethereadertheclearestpossibleideaofwhythistheorytakestheformitdoes,andwhyinthisformitdoessuchagoodjobofdescribingtherealworld.