g　in　muscles。　Many　good　remarks　are　scattered　throughout　this　volume；　to　which　I　shall　hereafter　refer。
  Short　discussions　on　Expression　may　be　found　in　various　works；　which　need　not　here　be　particularised。　　Mr。　Bain；　however；　in　two　of　his　works　has　treated　the　subject　at　some　length。　He　says；＇8＇　〃I　look　upon　the　expression　so…called　as　part　and　parcel　of　the　feeling。　　I　believe　it　to　be　a　general　law　of　the　mind　that　along　with　the　fact　of　inward　feeling　or　consciousness；　there　is　a　diffusive　action　or　excitement　over　the　bodily　members。〃　In　another　place　he　adds；　〃A　very　considerable　number　of　the　facts　may　be　brought　under　the　following　principle：　　namely；　that　states　of　pleasure　are　connected　with　an　increase；　and　states　of　pain　with　an　abatement；　of　some；　or　all；　of　the　vital　functions。〃　But　the　above　law　of　the　diffusive　action　of　feelings　seems　too　general　to　throw　much　light　on　special　expressions。
  Mr。　Herbert　Spencer；　in　treating　of　the　Feelings　in　his　‘Principles　of　Psychology'　（1855）；　makes　the　following　remarks：〃Fear；　when　strong；　expresses　itself　in　cries；　in　efforts　to　hide　or　escape；　in　palpitations　and　tremblings；　and　these　are　just　the　manifestations　that　would　accompany　an　actual　experience　of　the　evil　feared。　The　destructive　passions　are　shown　in　a　general　tension　of　the　muscular　system；　in　gnashing　of　the　teeth　and　protrusion　of　the　claws；　in　dilated　eyes　and　nostrils　in　growls；　and　these　are　weaker　forms　of　the　actions　that　accompany　the　killing　of　prey。〃　Here　we　have；　as　I　believe；　the　true　theory　of　a　large　number　of　expressions；　but　the　chief　interest　and　difficulty　of　the　subject　lies　in　following　out　the　wonderfully　complex　results。　I　infer　that　some　one　（but　who　he　is　I　have　not　been　able　to　ascertain）　formerly　advanced　a　nearly　similar　view；　for　Sir　C。　Bell　says；＇9＇　〃It　has　been　maintained　that　what　are　called　the　external　signs　of　passion；　are　only　the　concomitants　of　those　voluntary　movements　which　the　structure　renders　necessary。〃　　Mr。　Spencer　has　also　published＇10＇　a　valuable　essay　on　the　physiology　of　Laughter；　in　which　he　insists　on　〃the　general　law　that　feeling　passing　a　certain　pitch；　habitually　vents　itself　in　bodily　action；〃　and　that　〃an　overflow　of　nerve…force　undirected　by　any　motive；　will　manifestly　take　first　the　most　habitual　routes；　and　if　these　do　not　suffice；　will　next　overflow　into　the　less　habitual　ones。〃　This　law　I　believe　to　be　of　the　highest　importance　in　throwing　light　on　our　subject。‘
  ＇8＇　‘The　Senses　and　the　Intellect；'　2nd　edit。　　1864；　pp。　　96　and　288。　The　preface　to　the　first　edition　of　this　work　is　dated　June；　1855。　See　also　the　2nd　edition　of　Mr。　Bain's　work　on　the　‘Emotions　and　Will。'
  ＇9＇　‘The　Anatomy　of　Expression；'　3rd　edit。　　p。　　121。
  ＇10＇　‘Essays；　Scientific；　Political；　and　Speculative；'　Second　Series；　1863；　p。　　111。　　There　is　a　discussion　on　Laughter　in　the　First　Series　of　Essays；　which　discussion　seems　to　me　of　very　inferior　value。
  ＇11＇　Since　the　publication　of　the　essay　just　referred　to；　Mr。　Spencer　has　written　another；　on　〃Morals　and　Moral　Sentiments；〃　in　the　‘Fortnightly　Review；'　April　1；　1871；　p。　　426。　　He　has；　also；　now　published　his　final　conclusions　in　vol。　　ii。　　of　the　second　edit。　of　the　‘Principles　of　Psychology；'　1872；　p。　　539。　　I　may　state；　in　order　that　I　may　not　be　accused　of　trespassing　on　Mr。　Spencer's　domain；　that　I　announced　in　my　‘Descent　of　Man；'　that　I　had　then　written　a　part　of　the　present　volume：　　my　first　MS。　notes　on　the　subject　of　expression　bear　the　date　of　the　year　1838。
  All　the　authors　who　have　written　on　Expression；　with　the　exception　of　Mr。　Spencerthe　great　expounder　of　the　principle　of　Evolution　appear　to　have　been　firmly　convinced　that　species；　man　of　course　included；　came　into　existence　in　their　present　condition。　Sir　C。　Bell；　being　thus　convinced；　maintains　that　many　of　our　facial　muscles　are　〃purely　instrumental　in　expression；〃　or　are　〃a　special　provision〃　for　this　sole　object。＇12＇　But　the　simple　fact　that　the　anthropoid　apes　possess　the　same　facial　muscles　as　we　do；＇13＇　renders　it　very　improbable　that　these　muscles　in　our　case　serve　exclusively　for　expression；　for　no　one；　I　presume；　would　be　inclined　to　admit　that　monkeys　have　been　endowed　with　special　muscles　solely　for　exhibiting　their　hideous　grimaces。　Distinct　uses；　independently　of　expression；　can　indeed　be　assigned　with　much　probability　for　almost　all　the　facial　muscles。
  Sir　C。　Bell　evidently　wished　to　draw　as　broad　a　distinction　as　possible　between　man　and　the　lower　animals；　and　he　consequently　asserts　that　with　〃the　lower　creatures　there　is　no　expression　but　what　may　be　referred；　more　or　less　plainly；　to　their　acts　of　volition　or　necessary　instincts。〃　He　further　maintains　that　their　faces　〃seem　chiefly　capable　of　expressing　rage　and　fear。〃＇14＇　But　man　himself　cannot　express　love　and　humility　by　external　signs；　so　plainly　as　does　a　dog；　when　with　drooping　ears；　hanging　lips；　flexuous　body；　and　wagging　tail；　he　meets　his　beloved　master。　Nor　can　these　movements　in　the　dog　be　explained　by　acts　of　volition　or　necessary　instincts；　any　more　than　the　beaming　eyes　and　smiling　cheeks　of　a　man　when　he　meets　an　old　friend。　　If　Sir　C。　Bell　had　been　questioned　about　the　expression　of　affection　in　the　dog；　he　would　no　doubt　have　answered　that　this　animal　had　been　created　with　special　instincts；　adapting　him　for　association　with　man；　and　that　all　further　enquiry　on　the　subject　was　superfluous。
  ＇12＇　‘Anatomy　of　Expression；'　3rd　edit。　　pp。　　98；　121；　131。
  ＇13＇　Professor　Owen　expressly　states　（Proc。　Zoolog。　　Soc。　　1830；　p。　28）　that　this　is　the　case　with　respect　to　the　Orang；　and　specifies　all　the　more　important　muscles　which　are　well　known　to　serve　with　man　for　the　expression　of　his　feelings。　　See；　also；　a　description　of　several　of　the　facial　muscles　in　the　Chimpanzee；　by　Prof。　Macalister；　in　‘Annals　and　Magazine　of　Natural　History；'　vol。　　vii。　　May；　1871；　p。　　342。
  ＇14＇　‘Anatomy　of　Expression；'　pp。　　121；　138。
  Although　Gratiolet　emphatically　denies＇15＇　that　any　muscle　has　been　developed　solely　for　the　sake　of　expression；　he　seems　never　to　have　reflected　on　the　principle　of　evolution。　He　apparently　looks　at　each　species　as　a　separate　creation。　So　it　is　with　the　other　writers　on　Expression。　　For　instance；　Dr。　Duchenne；　after　speaking　of　the　movements　of　the　limbs；　refers　to　those　which　give　expression　to　the　face；　and　remarks：＇16＇　〃Le　createur　n'a　donc　pas　eu　a　se　preoccuper　ici　des　besoins　de　la　mecanique；　il　a　pu；　selon　sa　sagesse；　ouque　l'on　me　pardonne　cette　maniere　de　parlerpar　une　divine　fantaisie；　mettre　en　action　tel　ou　tel　muscle；　un　seul　ou　plusieurs　muscles　a　la　fois；　lorsqu'il　a　voulu　que　les　signes　caracteristiques　des　passions；　meme　les　plus　fugaces；　lussent　ecrits　passagerement　sur　la　face　de　l'homme。　Ce　langage　de　la　physionomie　une　fois　cree；　il　lui　a　suffi；　pour　le　rendre　universel　et　immuable；　de　donner　a　tout　etre　humain　la　faculte　instinctive　d'exprimer　toujours　ses　sendments　par　la　contraction　des　memes　muscles。〃
  Many　writers　consider　the　whole　subject　of　Expression　as　inexplicable。　Thus　the　illustrious　physiologist　Muller；　says；＇17＇　〃The　completely　different　expression　of　the　features　in　different　passions　shows　that；　according　to　the　kind　of　feeling　excited；　entirely　different　groups　of　the　fibres　of　the　facial　nerve　are　acted　on。　　Of　the　cause　of　this　we　are　quite　ignorant。〃
  ＇15＇　‘De　la　Physionomie；'　pp。　　12；　73。
  ＇16＇　‘Mecanisme　de　la　Physionomie　Humaine；'　8vo　edit。　　p。　　31。
  ＇17＇　‘Elements　of　Physiology；'　English　translation；　vol。　　ii。　　p。　　934。
  No　doubt　as　long　as　man　and　all　other　animals　are　viewed　as　independent　creations；　an　effectual　stop　is　put　to　our　natural　desire　to　investigate　as　far　as　possible　the　causes　of　Expression。　　By　this　doctrine；　anything　and　everything　can　be　equally　well　explained；　and　it　has　proved　as　pernicious　with　respect　to　Expression　as　to　every　other　branch　of　natural　history。　With　mankind　some　expressions；　such　as　the　bristling　of　the　hair　under　the　influence　of　extreme　terror；　or　the　uncovering　of　the　teeth　under　that　of　furious　rage；　can　hardly　be　understood；　except　on　the　belief　that　man　once　existed　in　a　much　lower　and　animal…like　condition。　The　community　of　certain　expressions　in　distinct　though　allied　species；　as　in　the　movements　of　the　same　facial　muscles　during　laughter　by　man　and　by　various　monkeys；　is　rendered　somewhat　more　intelligible；　if　we　believe　in　their　descent　from　a　common　progenitor。　He　who　admits　on　general　grounds　that　the　structure　and　habits　of　all　animals　have　been　gradually　evolved；　will　look　at　the　whole　subject　of　Expression　in　a　new　and　interesting　light。
  The　study　of　Expression　is　difficult；　owing　to　the　movements　being　often　extremely　slight；　and　of　a　fleeting　nature。　A　difference　may　be　clearly　perceived；　and　yet　it　may　be　impossible；　at　least　I　have　found　it　so；　to　state　in　what　the　difference　consists。　When　we　witness　any　deep　emotion；　our　sympathy　is　so　strongly　excited；　that　close　observation　is　forgotten　or　rendered　almost　impossible；　of　which　fact　I　have　had　many　curious　proofs。　Our　imagination　is　another　and　still　more　serious　source　of　error；　for　if　from　the　nature　of　the　circumstances　we　expect　to　see　any　expression；　we　readily　imagine　its　presence。　Notwith