commonly　gives　to　the　countenance；　as　Sir　C。　Bell　remarks；　an　aspect　of　intellectual　energy。　But　in　order　that　this　effect　may　be　produced；　the　eyes　must　be　clear　and　steady；　or　they　may　be　cast　downwards；　as　often　occurs　in　deep　thought。　　The　countenance　must　not　be　otherwise　disturbed；　as　in　the　case　of　an　ill…tempered　or　peevish　man；　or　of　one　who　shows　the　effects　of　prolonged　suffering；　with　dulled　eyes　and　drooping　jaw；　or　who　perceives　a　bad　taste　in　his　food；　or　who　finds　it　difficult　to　perform　some　trifling　act；　such　as　threading　a　needle。　　In　these　cases　a　frown　may　often　be　seen；　but　it　will　be　accompanied　by　some　other　expression；　which　will　entirely　prevent　the　countenance　having　an　appearance　of　intellectual　energy　or　of　profound　thought。
  ＇4＇　‘History　of　the　Abipones；'　Eng。　　translat。　　vol。　　ii。　　p。　　59；　as　quoted　by　Lubbock；　‘Origin　of　Civilisation；'　1870；　p。　　355。
  We　may　now　inquire　how　it　is　that　a　frown　should　express　the　perception　of　something　difficult　or　disagreeable；　either　in　thought　or　action。　In　the　same　way　as　naturalists　find　it　advisable　to　trace　the　embryological　development　of　an　organ　in　order　fully　to　understand　its　structure；　so　with　the　movements　of　expression　it　is　advisable　to　follow　as　nearly　as　possible　the　same　plan。　　The　earliest　and　almost　sole　expression　seen　during　the　first　days　of　infancy；　and　then　often　exhibited　is　that　displayed　during　the　act　of　screaming；　and　screaming　is　excited；　both　at　first　and　for　some　time　afterwards；　by　every　distressing　or　displeasing　sensation　and　emotion；by　hunger；　pain；　anger；　jealousy；　fear；　&c。　At　such　times　the　muscles　round　the　eyes　are　strongly　contracted；　and　this；　as　I　believe；　explains　to　a　large　extent　the　act　of　frowning　during　the　remainder　of　our　lives。　　I　repeatedly　observed　my　own　infants；　from　under　the　age　of　one　week　to　that　of　two　or　three　months；　and　found　that　when　a　screaming…fit　came　on　gradually；　the　first　sign　was　the　contraction　of　the　corrugators；　which　produced　a　slight　frown；　quickly　followed　by　the　contraction　of　the　other　muscles　round　the　eyes。　When　an　infant　is　uncomfortable　or　unwell；　little　frownsas　I　record　in　my　notesmay　be　seen　incessantly　passing　like　shadows　over　its　face；　these　being　generally；　but　not　always；　followed　sooner　or　later　by　a　crying…fit。　For　instance；　I　watched　for　some　time　a　baby；　between　seven　and　eight　weeks　old；　sucking　some　milk　which　was　cold；　and　therefore　displeasing　to　him；　and　a　steady　little　frown　was　maintained　all　the　time。　This　was　never　developed　into　an　actual　crying…fit；　though　occasionally　every　stage　of　close　approach　could　be　observed。
  As　the　habit　of　contracting　the　brows　has　been　followed　by　infants　during　innumerable　generations；　at　the　commencement　of　every　crying　or　screaming　fit；　it　has　become　firmly　associated　with　the　incipient　sense　of　something　distressing　or　disagreeable。　Hence　under　similar　circumstances　it　would　be　apt　to　be　continued　during　maturity；　although　never　then　developed　into　a　crying…fit。　Screaming　or　weeping　begins　to　be　voluntarily　restrained　at　an　early　period　of　life；　whereas　frowning　is　hardly　ever　restrained　at　any　age。　It　is　perhaps　worth　notice　that　with　children　much　given　to　weeping；　anything　which　perplexes　their　minds；　and　which　would　cause　most　other　children　merely　to　frown；　readily　makes　them　weep。　So　with　certain　classes　of　the　insane；　any　effort　of　mind；　however　slight；　which　with　an　habitual　frowner　would　cause　a　slight　frown；　leads　to　their　weeping　in　an　unrestrained　manner。　It　is　not　more　surprising　that　the　habit　of　contracting　the　brows　at　the　first　perception　of　something　distressing；　although　gained　during　infancy；　should　be　retained　during　the　rest　of　our　lives；　than　that　many　other　associated　habits　acquired　at　an　early　age　should　be　permanently　retained　both　by　man　and　the　lower　animals。　For　instance；　full…grown　cats；　when　feeling　warm　and　comfortable；　often　retain　the　habit　of　alternately　protruding　their　fore…feet　with　extended　toes；　which　habit　they　practised　for　a　definite　purpose　whilst　sucking　their　mothers。
  Another　and　distinct　cause　has　probably　strengthened　the　habit　of　frowning；　whenever　the　mind　is　intent　on　any　subject　and　encounters　some　difficulty。　Vision　is　the　most　important　of　all　the　senses；　and　during　primeval　times　the　closest　attention　must　have　been　incessantly：　　directed　towards　distant　objects　for　the　sake　of　obtaining　prey　and　avoiding　danger。　I　remember　being　struck；　whilst　travelling　in　parts　of　South　America；　which　were　dangerous　from　the　presence　of　Indians；　how　incessantly；　yet　as　it　appeared　unconsciously；　the　half…wild　Gauchos　closely　scanned　the　whole　horizon。　　Now；　when　any　one　with　no　covering　on　his　head　（as　must　have　been　aboriginally　the　case　with　mankind）；　strives　to　the　utmost　to　distinguish　in　broad　daylight；　and　especially　if　the　sky　is　bright；　a　distant　object；　he　almost　invariably　contracts　his　brows　to　prevent　the　entrance　of　too　much　light；　the　lower　eyelids；　cheeks；　and　upper　lip　being　at　the　same　time　raised；　so　as　to　lessen　the　orifice　of　the　eyes。　　I　have　purposely　asked　several　persons；　young　and　old；　to　look；　under　the　above　circumstances；　at　distant　objects；　making　them　believe　that　I　only　wished　to　test　the　power　of　their　vision；　and　they　all　behaved　in　the　manner　just　described。　Some　of　them；　also；　put　their　open；　flat　hands　over　their　eyes　to　keep　out　the　excess　of　light。　　Gratiolet；　after　making　some　remarks　to　nearly　the　same　effect；＇5＇　says；　〃Ce　sont　la　des　attitudes　de　vision　difficile。〃　He　concludes　that　the　muscles　round　the　eyes　contract　partly　for　the　sake　of　excluding　too　much　light　（which　appears　to　me　the　more　important　end）；　and　partly　to　prevent　all　rays　striking　the　retina；　except　those　which　come　direct　from　the　object　that　is　scrutinized。　Mr。　Bowman；　whom　I　consulted　on　this　point；　thinks　that　the　contraction　of　the　surrounding　muscles　may；　in　addition；　〃partly　sustain　the　consensual　movements　of　the　two　eyes；　by　giving　a　firmer　support　while　the　globes　are　brought　to　binocular　vision　by　their　own　proper　muscles。〃
  As　the　effort　of　viewing　with　care　under　a　bright　light　a　distant　object　is　both　difficult　and　irksome；　and　as　this　effort　has　been　habitually　accompanied；　during　numberless　generations；　by　the　contraction　of　the　eyebrows；　the　habit　of　frowning　will　thus　have　been　much　strengthened；　although　it　was　originally　practised　during　infancy　from　a　quite　independent　cause；　namely　as　the　first　step　in　the　protection　of　the　eyes　during　screaming。　There　is；　indeed；　much　analogy；　as　far　as　the　state　of　the　mind　is　concerned；　between　intently　scrutinizing　a　distant　object；　and　following　out　an　obscure　train　of　thought；　or　performing　some　little　and　troublesome　mechanical　work。　The　belief　that　the　habit　of　contracting　the　brows　is　continued　when　there　is　no　need　whatever　to　exclude　too　much　light；　receives　support　from　the　cases　formerly　alluded　to；　in　which　the　eyebrows　or　eyelids　are　acted　on　under　certain　circumstances　in　a　useless　manner；　from　having　been　similarly　used；　under　analogous　circumstances；　for　a　serviceable　purpose。　For　instance；　we　voluntarily　close　our　eyes　when　we　do　not　wish　to　see　any　object；　and　we　are　apt　to　close　them；　when　we　reject　a　proposition；　as　if　we　could　not　or　would　not　see　it；　or　when　we　think　about　something　horrible。　　We　raise　our　eyebrows　when　we　wish　to　see　quickly　all　round　us；　and　we　often　do　the　same；　when　we　earnestly　desire　to　remember　something；　acting　as　if　we　endeavoured　to　see　it。
  ＇5＇　‘De　la　Physionomie；'　pp。　　15；　144；　146。　　Mr。　Herbert　Spencer　accounts　for　frowning　exclusively　by　the　habit　of　contracting　the　brows　as　a　shade　to　the　eyes　in　a　bright　light：　see　‘Principles　of　Physiology；'　2nd　edit。　　1872；　p。　　546。
  _Abstraction。　　Meditation_。When　a　person　is　lost　in　thought　with　his　mind　absent；　or；　as　it　is　sometimes　said；　〃when　he　is　in　a　brown　study；〃　he　does　not　frown；　but　his　eyes　appear　vacant。　The　lower　eyelids　are　generally　raised　and　wrinkled；　in　the　same　manner　as　when　a　short…sighted　person　tries　to　distinguish　a　distant　object；　and　the　upper　orbicular　muscles　are　at　the　same　time　slightly　contracted。　The　wrinkling　of　the　lower　eyelids　under　these　circumstances　has　been　observed　with　some　savages；　as　by　Mr。　Dyson　Lacy　with　the　Australians　of　Queensland；　and　several　times　by　Mr。　Geach　with　the　Malays　of　the　interior　of　Malacca。　　What　the　meaning　or　cause　of　this　action　may　be；　cannot　at　present　be　explained；　but　here　we　have　another　instance　of　movement　round　the　eyes　in　relation　to　the　state　of　the　mind。
  The　vacant　expression　of　the　eyes　is　very　peculiar；　and　at　once　shows　when　a　man　is　completely　lost　in　thought。　　Professor　Donders　has；　with　his　usual　kindness；　investigated　this　subject　for　me。　He　has　observed　others　in　this　condition；　and　has　been　himself　observed　by　Professor　Engelmann。　　The　eyes　are　not　then　fixed　on　any　object；　and　therefore　not；　as　I　had　imagined；　on　some　distant　object。　The　lines　of　vision　of　the　two　eyes　even　often　become　slightly　divergent；　the　divergence；　if　the　head　be　held　vertically；　with　the　plane　of　vision　horizontal；　amounting　to　an　angle　of　2'0　as　a　maximum。　This　was　ascertained　by　observing　the　crossed　double　image　of　a　distant　object。　　When　the　head　d