Forcedoesnotadmitofexplanation，norofproperdefinition，anymorethanthehypotheticalsubstratumofmatter。IfweassumetheInfiniteasomnipresent，omniscient，omnipotent，wecannotsupposeHimexcludedfromanypartofHiscreation，exceptfromrebellioussoulswhichvoluntarilyexcludeHimbytheexerciseoftheirfatalprerogativeoffree-will。Force，then，istheactofimmanentDivinity。Ifindnomeaninginmechanicalexplanations。Newton’shypothesisofanetherfillingtheheavenlyspacesdoesnot，I
　　confess，helpmyconceptions。Iwill，andthemusclesofmyvocalorgansshapemyspeech。Godwills，andtheuniversearticulatesHispower，wisdom，andgoodness。ThatisallIknow。Thereisnobridgemymindcanthrowfromthe“immaterial“causetothe“material“
　　effect。
　　Theproblemofforcemeetsuseverywhere，andIprefertoencounteritintheworldofphysicalphenomenabeforereachingthatoflivingactions。Itisonlythenamefortheincomprehensiblecauseofcertainchangesknowntoourconsciousness，andassumedtobeoutsideofit。FormeitistheDeityHimselfinaction。
　　IcanthereforeseealargesignificanceinthesomewhatboldlanguageofBurdach：“Thereisformebutonemiracle，thatofinfiniteexistence，andbutonemystery，themannerinwhichthefiniteproceedsfromtheinfinite。Sosoonaswerecognizethisincomprehensibleactasthegeneralandprimordialmiracle，ofwhichourreasonperceivesthenecessity，butthemannerofwhichourintelligencecannotgrasp，sosoonaswecontemplatethenatureknowntousbyexperienceinthislight，thereisforusnootherimpenetrablemiracleormystery。“
　　Letusturntoabranchofknowledgewhichdealswithcertaintiesuptothelimitofthesenses，andisinvolvedinnospeculationsbeyondthem。Incertainpointsofview，HUMANANATOMYmaybeconsideredanalmostexhaustedscience。Fromtimetotimesomesmallorganwhichhadescapedearlierobservershasbeenpointedout，——suchpartsasthetensortarsi，theoticganglion，orthePacinianbodies；butsomeofourbestanatomicalworksarethosewhichhavebeenclassicformanygenerations。TheplatesofthebonesinVesalius，threecenturiesold，arestillmasterpiecesofaccuracy，asofart。ThemagnificentworkofAlbinusonthemuscles，publishedin1747，isstillsupremeinitsdepartment，astheconstantreferencesofthemostthoroughrecenttreatiseonthesubject，thatofTheile，sufficientlyshow。Morehasbeendoneinunravellingthemysteriesofthefasciae，buttherehasbeenatendencytooverdothiskindofmaterialanalysis。AlexanderThomsonsplitthemupintocobwebs，asyoumayseeintheplatestoVelpeau’sSurgicalAnatomy。IwellrememberhowheusedtoshakehisheadoverthecoarseworkofScarpaandAstleyCooper，——asifDenner，whopaintedtheseparatehairsofthebeardandporesoftheskininhisportraits，hadspokenlightlyofthepicturesofRubensandVandyk。
　　Notonlyhaslittlebeenaddedtothecatalogueofparts，butsomethingslongknownhadbecomehalf-forgotten。Louisandothersconfoundedthesolitaryglandsofthelowerpartofthesmallintestinewiththosewhich“thegreatBrunner，“asHallercallshim，describedin1687asbeingfoundintheduodenum。ThedisplayofthefibrousstructureofthebrainseemedanoveltyasshownbySpurzheim。OneisstartledtofindthemethodanticipatedbyRaymondVieussensnearlytwocenturiesago。IcanhardlythinkGordonhadeverlookedathisfigures，thoughhenamestheirauthor，whenhewrotethecaptiousandsneeringarticlewhichattractedsomuchattentioninthepagesofthe“EdinburghReview。“
　　Thisistheplace，ifanywhere，tomentionanyobservationsIcouldpretendtohavemadeinthecourseofmyteachingthestructureofthehumanbody。Icanmakenobettershowthanmostofmypredecessorsinthiswell-reapedfield。Thenucleatedcellsfoundconnectedwiththecancellatedstructureofthebones，whichIfirstpointedoutandhadfiguredin1847，andhaveshownyearlyfromthattimetothepresent，andthefossamasseterica，ashallowconcavityontheramusofthelowerjaw，forthelodgmentofthemassetermuscle，whichacquiressignificancewhenexaminedbythesideofthedeepcavityonthecorrespondingpartinsomecarnivoratowhichitanswers，mayperhapsbeclaimedasdeservingattention。Ihavealsopleasedmyselfbymakingaspecialgroupofthesixradiatingmuscleswhichdivergefromthespineoftheaxis，orsecondcervicalvertebra，andbygivingtoitthenamestellamusculosanuchaee。Butthisscantycatalogueisonlyanevidencethatonemayteachlongandseelittlethathasnotbeennotedbythosewhohavegonebeforehim。
　　OfcourseIdonotthinkitnecessarytoincluderare，butalreadydescribedanomalies，suchastheepisternalbones，therectussternalis，andotherinterestingexceptionalformationsIhaveencountered，whichhaveshownacurioustendencytopresentthemselvesseveraltimesinthesameseason，perhapsbecausethefirstspecimenfoundcallsourattentiontoanywemaysubsequentlymeetwith。
　　Theanatomyofthescalpelandtheamphitheatrewas，then，becominganexhaustedbranchofinvestigation。Butduringthepresentcenturythestudyofthehumanbodyhaschangeditsoldaspect，andbecomefertileinnewobservations。Thisrejuvenescencewaseffectedbymeansoftwoprincipalagencies，——newmethodsandanewinstrument。
　　Descriptiveanatomy，asknownfromanearlydate，istothebodywhatgeographyistotheplanet。NowgeographywasprettywellknownsolongagoaswhenArrowsmith，whowasbornin1750，publishedhisadmirablemaps。ButinthatsameyearwasbornWerner，whotaughtanewwayofstudyingtheearth，sincebecomefamiliartousallunderthenameofGeology。
　　Whatgeologyhasdoneforourknowledgeoftheearth，hasbeendoneforourknowledgeofthebodybythatmethodofstudytowhichisgiventhenameofGeneralAnatomy。Itstudies，nottheorgansassuch，buttheelementsoutofwhichtheorgansareconstructed。Itisthegeologyofthebody，asthatisthegeneralanatomyoftheearth。TheextraordinarygeniusofBichat，towhommorethananyotherweowethisnewmethodofstudy，doesnotrequireMr。Buckle’stestimonytoimpressthepractitionerwiththeimportanceofitsachievements。IhaveheardaverywisephysicianquestionwhetheranyimportantresulthadaccruedtopracticalmedicinefromHarvey’sdiscoveryofthecirculation。ButAnatomy，Physiology，andPathologyhavereceivedanewlightfromthisnovelmethodofcontemplatingthelivingstructures，whichhashadavastinfluenceinenablingthepractitioneratleasttodistinguishandpredictthecourseofdisease。Weknowaswellwhatdifferencestoexpectinthehabitsofamucousandofaserousmembrane，aswhatmineralsubstancestolookforinthechalkorthecoalmeasures。YouhaveonlytoreadCullen’sdescriptionofinflammationofthelungsorofthebowels，andcompareitwithsuchasyoumayfindinLaennecorWatson，toseetheimmensegainwhichdiagnosisandprognosishavederivedfromgeneralanatomy。
　　Thesecondnewmethodofstudyingthehumanstructure，beginningwiththelaborsofScarpa，Burns，andColles，grewupprincipallyduringthefirstthirdofthiscentury。Itdoesnotdealwithorgans，asdidtheearlieranatomists，norwithtissues，afterthemannerofBichat。Itmapsthewholesurfaceofthebodyintoanarbitrarynumberofregions，andstudieseachregionsuccessivelyfromthesurfacetothebone，orbeneathit。Thishardlydeservesthenameofascience，althoughVelpeauhasdignifieditwiththattitle，butitfurnishesanadmirablepracticalwayforthesurgeonwhohastooperateonaparticularregionofthebodytostudythatregion。Ifwearebuyingafarm，wearenotcontentwiththeStatemaporageologicalchartincludingtheestateinquestion。Wedemandanexactsurveyofthatparticularproperty，sothatwemayknowwhatwearedealingwith。Thisisjustwhatregional，or，asitissometimescalled，surgicalanatomy，doesforthesurgeonwithreferencetothepartonwhichhisskillistobeexercised。Itenableshimtoseewiththemind’seyethroughtheopaquetissuesdowntotheboneonwhichtheylie，asiftheskinweretransparentasthecornea，andtheorgansitcoverstranslucentasthegelatinouspulpofamedusa。
　　ItiscuriousthattheJapaneseshouldhaveanticipatedEuropeinakindofruderegionalanatomy。IhaveseenamanikinofJapanesemaketracedalloverwithlines，andpointsmarkingtheirintersection。Bythistheirdoctorsareguidedintheperformanceofacupuncture，markingthesafeplacestothrustinneedles，aswebuoyoutourship-channels，anddoubtlessindicatingtolearnedeyesthespotswhereincautiousmeddlinghadledtothoselittleaccidentsofshipwrecktowhichpatientsareunfortunatelyliable。
　　Achangeofmethod，then，hasgivenusGeneralandRegionalAnatomy。
　　These，too，havebeenworkedsothoroughly，that，ifnotexhausted，theyhaveatleastbecometoagreatextentfixedandpositivebranchesofknowledge。Butthefirstofthem，GeneralAnatomy，wouldnever，havereachedthispositiveconditionbutfortheintroductionofthat，instrumentwhichIhavementionedasthesecondgreataidtomodernprogress。
　　Thisinstrumentistheachromaticmicroscope。Forthehistoryofthesuccessivestepsbywhichitbecametheeffectivescientificimplementwenowpossess，ImustreferyoutotheworkofMr。
　　Quekett，toanexcellentarticleinthe“PennyCyclopaedia，“ortothatofSirDavidBrewsterinthe“EncyclopaediaBritannica。“Itisamostinterestingpieceofscientifichistory，whichshowshowtheproblemwhichBiotin1821pronouncedinsolvablewasinthecourseofafewyearspracticallysolved，withasuccessequaltothatwhichDollondhadlongbeforeobtainedwiththetelescope。Itisenoughforourpurposethatwearenowinpossessionofaninstrumentfreedfromallconfusionsandillusions，whichmagnifiesathousanddiameters，——amilliontimesinsurface，——withoutseriousdistortionordiscolorationofitsobject。
　　Aquarterofacenturyago，oralittlemore，aninstructorwouldnothavehesitatedtoputJohnBell’s“Anatomy“andBostock’s“Physiology“intoastudent’shands，asgoodauthorityontheirrespectivesubjects。Letusnotbeunjusttoeitheroftheseauthors。JohnBellistheliveliestmedicalwriterthatIcanrememberwhohaswrittensincethedaysofdelightfuloldAmbroisePare。Hispicturesquedescriptionsandboldfiguresareasgoodnowastheyeverwere，andhisbookcanneverbecomeobsolete。ButlistentowhatJohnBellsaysofthemicroscope：
　　“Philosophersofthelastagehadbeenatinfinitepainstofindtheultimatefibreofmuscles，thinkingtodiscoveritspropertiesinitsform；buttheysawjustinproportiontotheglasseswhichtheyused，ortotheirpracticeandskillinthatart，whichisnowalmostforsaken。“
　　Dr。Bostock’swork，neglectedasitis，isonewhichIvalueveryhighlyasareallylearnedcompilation，fulloforiginalreferences。
　　ButDr。Bostocksays：“Muchasthenaturalisthasbeenindebtedtothemicroscope，bybringingintoviewmanybeingsofwhichhecouldnototherwisehaveascertainedtheexistence，thephysiologisthasnotyetderivedanygreatbenefitfromtheinstrument。“
　　Theseareonlyspecimensofthemannerinwhichthemicroscopeanditsresultsweregenerallyregardedbythegenerationjustprecedingourown。
　　Ihavereferredyoutotheproperauthoritiesfortheaccountofthoseimprovementswhichabouttheyear1830renderedthecompoundmicroscopeanefficientandtrustworthyinstrument。Itwasnowforthefirsttimethatatruegeneralanatomybecamepossible。Asearlyas1816Treviranushadattemptedtoresolvethetissues，ofwhichBichathadadmittednolessthantwenty-one，intotheirsimplemicroscopicelements。Howcouldsuchanattemptsucceed，Henlewellasks，atatimewhenthemostextensivelydiffusedofallthetissues，theareolar，wasnotatallunderstood？AllthatmethodcoulddohadbeenaccomplishedbyBichatandhisfollowers。Itwasfortheopticiantotakethenextstep。Thefutureofanatomyandphysiology，asanenthusiasticmicrologistofthetimesaid，wasinthehandsofMessrs。SchieckandPistor，famousopticiansofBerlin。
　　InthoseearlierdaysofwhichIamspeaking，allthepointsofminuteanatomywereinvolvedinobscurity。Somefoundglobuleseverywhere，somefibres。Studentsdisputedwhethertheconjunctivaextendedoverthecorneaornot，andworriedthemselvesoverGaultierdeClaubry’sstratifiedlayersoftheskin，orBreschet’sblennogenousandchromatogenousorgans。Thedartoswasapuzzle，thecentralspinalcanalamyth，thedeciduaclothedinfableasmuchasthegoldenfleece。Thestructureofbone，nowsobeautifullymadeout，——eventhatoftheteeth，inwhicholdLeeuwenhoek，peepingwithhisoctogenarianeyesthroughtheminutelenseswroughtwithhisownhands，hadlongagoseenthe“pipes，“ashecalledthem，——washardlyknownatall。Theminutestructureofthevisceralayinthemistsofanuncertainmicroscopicvision。TheintimaterecessesoftheanimalsystemweretothestudentsofanatomywhattheanteriorofAfricalongwastogeographers，andthestoriesofmicroscopicexplorerswereasmuchsneeredatasthoseofBruceorDuChailly，andwithbetterreason。