asleep　as　when　you　are　awake。
  Well；　now；　you　cannot　at　the　moment　answer　that　kind　of　reasoning。
  You　feel　that　your　worthy　friend　has　you　somewhat　at　a
  disadvantage。　　You　will　feel　perfectly　convinced　in　your　own　mind；
  however；　that　you　are　quite　right；　and　you　say　to　him；　〃My　good
  friend；　I　can　only　be　guided　by　the　natural　probabilities　of　the
  case；　and　if　you　will　be　kind　enough　to　stand　aside　and　permit　me
  to　pass；　I　will　go　and　fetch　the　police。〃　　Well；　we　will　suppose
  that　your　journey　is　successful；　and　that　by　good　luck　you　meet
  with　a　policeman；　that　eventually　the　burglar　is　found　with　your
  property　on　his　person；　and　the　marks　correspond　to　his　hand　and　to
  his　boots。　　Probably　any　jury　would　consider　those　facts　a　very
  good　experimental　verification　of　your　hypothesis；　touching　the
  cause　of　the　abnormal　phenomena　observed　in　your　parlor；　and　would
  act　accordingly。
  Now；　in　this　supposititious　case；　I　have　taken　phenomena　of　a　very
  common　kind；　in　order　that　you　might　see　what　are　the　different
  steps　in　an　ordinary　process　of　reasoning；　if　you　will　only　take
  the　trouble　to　analyse　it　carefully。　　All　the　operations　I　have
  described；　you　will　see；　are　involved　in　the　mind　of　any　man　of
  sense　in　leading　him　to　a　conclusion　as　to　the　course　he　should
  take　in　order　to　make　good　a　robbery　and　punish　the　offender。　　I
  say　that　you　are　led；　in　that　case；　to　your　conclusion　by　exactly
  the　same　train　of　reasoning　as　that　which　a　man　of　science　pursues
  when　he　is　endeavouring　to　discover　the　origin　and　laws　of　the　most
  occult　phenomena。　　The　process　is；　and　always　must　be；　the　same；
  and　precisely　the　same　mode　of　reasoning　was　employed　by　Newton　＇90＇
  and　Laplace　＇91＇　in　their　endeavours　to　discover　and　define　the　causes
  of　the　movements　of　the　heavenly　bodies；　as　you；　with　your　own　common
  sense；　would　employ　to　detect　a　burglar。　　The　only　difference　is；
  that　the　nature　of　the　inquiry　being　more　abstruse；　every　step　has
  to　be　most　carefully　watched；　so　that　there　may　not　be　a　single
  crack　or　flaw　in　your　hypothesis。　　A　flaw　or　crack　in　many　of　the
  hypotheses　of　daily　life　may　be　of　little　or　no　moment　as　affecting
  the　general　correctness　of　the　conclusions　at　which　we　may　arrive；
  but；　in　a　scientific　inquiry；　a　fallacy；　great　or　small；　is　always
  of　importance；　and　is　sure　to　be　in　the　long　run　constantly
  productive　of　mischievous　if　not　fatal　results。
  Do　not　allow　yourselves　to　be　misled　by　the　common　notion　that　an
  hypothesis　is　untrustworthy　simply　because　it　is　an　hypothesis。　　It
  is　often　urged；　in　respect　to　some　scientific　conclusion；　that；
  after　all；　it　is　only　an　hypothesis。　　But　what　more　have　we　to
  guide　us　in　nine…tenths　of　the　most　important　affairs　of　daily　life
  than　hypotheses；　and　often　very　ill…based　ones？　　So　that　in
  science；　where　the　evidence　of　an　hypothesis　is　subjected　to　the
  most　rigid　examination；　we　may　rightly　pursue　the　same　course。　　You
  may　have　hypotheses；　and　hypotheses。　　A　man　may　say；　if　he　likes；
  that　the　moon　is　made　of　green　cheese：　that　is　an　hypothesis。　　But
  another　man；　who　has　devoted　a　great　deal　of　time　and　attention　to
  the　subject；　and　availed　himself　of　the　most　powerful　telescopes
  and　the　results　of　the　observations　of　others；　declares　that　in　his
  opinion　it　is　probably　composed　of　materials　very　similar　to　those
  of　which　our　own　earth　is　made　up：　and　that　is　also　only　an
  hypothesis。　　But　I　need　not　tell　you　that　there　is　an　enormous
  difference　in　the　value　of　the　two　hypotheses。　　That　one　which　is
  based　on　sound　scientific　knowledge　is　sure　to　have　a　corresponding
  value；　and　that　which　is　a　mere　hasty　random　guess　is　likely　to
  have　but　little　value。　　Every　great　step　in　our　progress　in
  discovering　causes　has　been　made　in　exactly　the　same　way　as　that
  which　I　have　detailed　to　you。　　A　person　observing　the　occurrence　of
  certain　facts　and　phenomena　asks；　naturally　enough；　what　process；
  what　kind　of　operation　known　to　occur　in　Nature　applied　to　the
  particular　case；　will　unravel　and　explain　the　mystery？　　Hence　you
  have　the　scientific　hypothesis；　and　its　value　will　be　proportionate
  to　the　care　and　completeness　with　which　its　basis　had　been　tested
  and　verified。　　It　is　in　these　matters　as　in　the　commonest　affairs
  of　practical　life：　the　guess　of　the　fool　will　be　folly；　while　the
  guess　of　the　wise　man　will　contain　wisdom。　　In　all　cases；　you　see
  that　the　value　of　the　result　depends　on　the　patience　and
  faithfulness　with　which　the　investigator　applies　to　his　hypothesis
  every　possible　kind　of　verification。
  ON　THE　PHYSICAL　BASIS　OF　LIFE　＇92＇
  In　order　to　make　the　title　of　this　discourse　generally
  intelligible；　I　have　translated　the　term　〃Protoplasm；〃　which　is　the
  scientific　name　of　the　substance　of　which　I　am　about　to　speak；　by
  the　words　〃the　physical　basis　of　life。〃　　I　suppose　that；　to　many；
  the　idea　that　there　is　such　a　thing　as　a　physical　basis；　or　matter；
  of　life　may　be　novelso　widely　spread　is　the　conception　of　life　as
  a　something　which　works　through　matter；　but　is　independent　of　it；
  and　even　those　who　are　aware　that　matter　and　life　are　inseparably
  connected；　may　not　be　prepared　for　the　conclusion　plainly　suggested
  by　the　phrase；　〃THE　physical　basis　or　matter　of　life；〃　that　there
  is　some　one　kind　of　matter　which　is　common　to　all　living　beings；
  and　that　their　endless　diversities　are　bound　together　by　a
  physical；　as　well　as　an　ideal；　unity。　　In　fact；　when　first
  apprehended；　such　a　doctrine　as　this　appears　almost　shocking　to
  common　sense。
  What；　truly；　can　seem　to　be　more　obviously　different　from　one
  another；　in　faculty；　in　form；　and　in　substance；　than　the　various
  kinds　of　living　beings？　　What　community　of　faculty　can　there　be
  between　the　bright…coloured　lichen；　which　so　nearly　resembles　a
  mere　mineral　incrustation　of　the　bare　rock　on　which　it　grows；　and
  the　painter；　to　whom　it　is　instinct　with　beauty；　or　the　botanist；
  whom　it　feeds　with　knowledge？
  Again；　think　of　the　microscopic　fungusa　mere　infinitesimal　ovoid
  particle；　which　finds　space　and　duration　enough　to　multiply　into
  countless　millions　in　the　body　of　a　living　fly；　and　then　of　the
  wealth　of　foliage；　the　luxuriance　of　flower　and　fruit；　which　lies
  between　this　bald　sketch　of　a　plant　and　the　giant　pine　of
  California；　towering　to　the　dimensions　of　a　cathedral　spire；　or　the
  Indian　fig；　which　covers　acres　with　its　profound　shadow；　and
  endures　while　nations　and　empires　come　and　go　around　its　vast
  circumference。　　Or；　turning　to　the　other　half　of　the　world　of　life；
  picture　to　yourselves　the　great　Finner　whale；＇93＇　hugest　of　beasts
  that　live；　or　have　lived；　disporting　his　eighty　or　ninety　feet　of　bone；
  muscle　and　blubber；　with　easy　roll；　among　waves　in　which　the
  stoutest　ship　that　ever　left　dockyard　would　flounder　hopelessly；
  and　contrast　him　with　the　invisible　animalculesmere　gelatinous
  specks；　multitudes　of　which　could；　in　fact；　dance　upon　the　point　of
  a　needle　with　the　same　ease　as　the　angels　of　the　Schoolmen　could；
  in　imagination。　　With　these　images　before　your　minds；　you　may　well
  ask；　what　community　of　form；　or　structure；　is　there　between　the
  animalcule　and　the　whale；　or　between　the　fungus　and　the　fig…tree？
  And；　a　fortiori；＇94＇　between　all　four？
  Finally；　if　we　regard　substance；　or　material　composition；　what
  hidden　bond　can　connect　the　flower　which　a　girl　wears　in　her　hair
  and　the　blood　which　courses　through　her　youthful　veins；　or；　what　is
  there　in　common　between　the　dense　and　resisting　mass　of　the　oak；　or
  the　strong　fabric　of　the　tortoise；　and　those　broad　disks　of　glassy
  jelly　which　may　be　seen　pulsating　through　the　waters　of　a　calm　sea；
  but　which　drain　away　to　mere　films　in　the　hand　which　raises　them
  out　of　their　element？
  Such　objections　as　these　must；　I　think；　arise　in　the　mind　of　every
  one　who　ponders；　for　the　first　time；　upon　the　conception　of　a
  single　physical　basis　of　life　underlying　all　the　diversities　of
  vital　existence；　but　I　propose　to　demonstrate　to　you　that；
  notwithstanding　these　apparent　difficulties；　a　threefold　unity
  namely；　a　unity　of　power　or　faculty；　a　unity　of　form；　and　a　unity
  of　substantial　compositiondoes　pervade　the　whole　living　world。
  No　very　abstruse　argumentation　is　needed；　in　the　first　place　to
  prove　that　the　powers；　or　faculties；　of　all　kinds　of　living　matter；
  diverse　as　they　may　be　in　degree；　are　substantially　similar　in
  kind。
  Goethe　has　condensed　a　survey　of　all　powers　of　mankind　into　the
  well…known　epigram：＇95＇
  〃Warum　treibt　sich　das　Volk　so　und　schreit？　　Es　will　sich　ernahren
  Kinder　zeugen；　und　die　nahren　so　gut　es　vermag。
  。　　　　。　　　　。　　　　。　　　　。　　　　。　　　　。　　　　。　　　　。　　　　。　　　　。　　　　。　　　　。
  Weiter　bringt　es　kein　Mensch；　stell'　er　sich　wie　er　auch　will。〃
  In　physiological　language　this　means；　that　all　the　multifarious　and
  complicated　activities　of　man　are　comprehensible　under　three
  categories。　　Either　they　are　immediately　directed　towards　the
  mainten