37。　　Such　is　the　art　of　warfare。
  ＇1＇　　See　Col。　Henderson；　op。　cit。　vol。　I。　p。　426。
  ＇2＇　　　For　a　number　of　maxims　on　this　head；　see　〃Marshal　Turenne〃
  （Longmans；　1907）；　p。　29。
  …
  VIII。　　VARIATION　IN　TACTICS
  ＇The　heading　means　literally　〃The　Nine　Variations；〃　but　as
  Sun　Tzu　does　not　appear　to　enumerate　these；　and　as；　　indeed；　　he
  has　already　told　us　（V　SS。　6…11）　that　such　deflections　from　the
  ordinary　course　are　practically　innumerable；　　we　have　little
  option　but　to　follow　Wang　Hsi；　who　says　that　〃Nine〃　stands　for　an
  indefinitely　large　number。　　〃All　it　means　is　that　in　warfare　we
  ought　to　very　our　tactics　to　the　utmost　degree。。。。　　I　do　not　know
  what　Ts‘ao　Kung　makes　these　Nine　Variations　out　to　be；　but　it　has
  been　suggested　that　they　are　connected　with　the　Nine　Situations〃
  …　of　chapt。　XI。　　This　is　the　view　adopted　by　Chang　Yu。　　The　only
  other　alternative　is　to　suppose　that　something　has　been　losta
  supposition　to　which　the　unusual　shortness　of　the　chapter　lends
  some　weight。＇
  1。　　　Sun　Tzu　said：　　　In　war；　　the　general　receives　his
  commands　from　the　sovereign；　collects　his　army　and　concentrates
  his　forces。
  ＇Repeated　from　VII。　ss。　1；　where　it　is　certainly　more　in
  place。　　It　may　have　been　interpolated　here　merely　in　order　to
  supply　a　beginning　to　the　chapter。＇
  2。　　When　in　difficult　country；　do　not　encamp。　　In　country
  where　high　roads　intersect；　join　hands　with　your　allies。　　Do　not
  linger　in　dangerously　isolated　positions。
  ＇The　last　situation　is　not　one　of　the　Nine　Situations　as
  given　in　the　beginning　of　chap。　XI；　but　occurs　later　on　　（ibid。
  ss。　43。　q。v。）。　　Chang　Yu　defines　this　situation　as　being　situated
  across　the　frontier；　in　hostile　territory。　　Li　Ch‘uan　says　it　is
  〃country　in　which　there　are　no　springs　or　wells；　flocks　or　herds；
  vegetables　or　firewood；〃　Chia　Lin；　〃one　of　gorges；　　chasms　and
  precipices；　without　a　road　by　which　to　advance。〃＇
  In　hemmed…in　situations；　　you　must　resort　to　stratagem。　　In
  desperate　position；　you　must　fight。
  3。　　There　are　roads　which　must　not　be　followed；
  ＇〃Especially　those　leading　through　narrow　defiles；〃　says　Li
  Ch‘uan；　〃where　an　ambush　is　to　be　feared。〃＇
  armies　which　must　be　not　attacked；
  ＇More　correctly；　perhaps；　〃there　are　times　when　an　army　must
  not　be　attacked。〃　　Ch‘en　Hao　says：　　〃When　you　see　your　way　to
  obtain　a　rival　advantage；　but　are　powerless　to　inflict　a　real
  defeat；　refrain　from　attacking；　for　fear　of　overtaxing　your　men's
  strength。〃＇
  towns　which　must　be　besieged；
  ＇Cf。　　III。　　ss。　　4　　　Ts‘ao　Kung　gives　　　an　　　interesting
  illustration　　　from　his　own　experience。　　When　invading　　　the
  territory　of　Hsu…chou；　he　ignored　the　city　of　Hua…pi；　which　lay
  directly　in　his　path；　and　pressed　on　into　the　heart　of　the
  country。　　This　excellent　strategy　was　rewarded　by　the　subsequent
  capture　of　no　fewer　than　fourteen　important　district　cities。
  Chang　Yu　says：　　〃No　town　should　be　attacked　which；　　if　taken；
  cannot　be　held；　or　if　left　alone；　will　not　cause　any　trouble。〃
  Hsun　Ying；　when　urged　to　attack　Pi…yang；　replied：　　〃The　city　is
  small　and　well…fortified；　even　if　I　succeed　intaking　it；　it　will
  be　no　great　feat　of　arms；　whereas　if　I　fail；　I　shall　make　myself
  a　laughing…stock。〃　　　In　the　seventeenth　century；　　sieges　still
  formed　a　large　proportion　of　war。　　It　was　Turenne　who　directed
  attention　to　the　importance　of　marches；　　countermarches　and
  maneuvers。　　He　said：　　〃It　is　a　great　mistake　to　waste　men　in
  taking　a　town　when　the　same　expenditure　of　soldiers　will　gain　a
  province。〃　＇1＇　＇
  positions　which　must　not　be　contested；　commands　of　the　sovereign
  which　must　not　be　obeyed。
  ＇This　is　a　hard　saying　for　the　Chinese；　with　their　reverence
  for　authority；　　and　Wei　Liao　Tzu　（quoted　by　Tu　Mu）　is　moved　to
  exclaim：　　　　〃Weapons　　　are　　　baleful　　　instruments；　　　strife　　　is
  antagonistic　to　virtue；　a　military　commander　is　the　negation　of
  civil　order！〃　　The　unpalatable　fact　remains；　however；　that　even
  Imperial　wishes　must　be　subordinated　to　military　necessity。＇
  4。　　The　general　who　thoroughly　understands　the　advantages
  that　accompany　variation　of　tactics　knows　how　to　handle　his
  troops。
  5。　　The　general　who　does　not　understand　these；　may　be　well
  acquainted　with　the　configuration　of　the　country；　yet　he　will　not
  be　able　to　turn　his　knowledge　to　practical　account。
  ＇Literally；　　〃get　the　advantage　of　the　ground；〃　which　means
  not　only　securing　good　positions；　but　availing　oneself　of　natural
  advantages　in　every　possible　way。　　Chang　Yu　says：　　〃Every　kind　of
  ground　is　characterized　by　certain　natural　features；　　and　also
  gives　scope　for　a　certain　variability　of　plan。　　How　it　is
  possible　to　turn　these　natural　features　to　account　unless
  topographical　knowledge　is　supplemented　by　versatility　of　mind？〃＇
  6。　　So；　the　student　of　war　who　is　unversed　in　the　art　of　war
  of　varying　his　plans；　even　though　he　be　acquainted　with　the　Five
  Advantages；　will　fail　to　make　the　best　use　of　his　men。
  ＇Chia　Lin　tells　us　that　these　imply　five　obvious　and
  generally　advantageous　lines　of　action；　namely：　　〃if　a　certain
  road　is　short；　it　must　be　followed；　if　an　army　is　isolated；　　it
  must　be　attacked；　if　a　town　is　in　a　parlous　condition；　it　must　be
  besieged；　if　a　position　can　be　stormed；　it　must　be　attempted；　and
  if　consistent　with　military　operations；　the　ruler's　commands　must
  be　obeyed。〃　　But　there　are　circumstances　which　sometimes　forbid　a
  general　to　use　these　advantages。　　For　instance；　〃a　certain　road
  may　be　the　shortest　way　for　him；　but　if　he　knows　that　it　abounds
  in　natural　obstacles；　or　that　the　enemy　has　laid　an　ambush　on　it；
  he　will　not　follow　that　road。　　A　hostile　force　may　be　open　to
  attack；　　but　if　he　knows　that　it　is　hard…pressed　and　likely　to
  fight　with　desperation；　he　will　refrain　from　striking；〃　　and　so
  on。＇
  7。　　Hence　in　the　wise　leader's　plans；　　considerations　of
  advantage　and　of　disadvantage　will　be　blended　together。
  ＇〃Whether　in　an　advantageous　position　or　a　disadvantageous
  one；〃　　says　Ts‘ao　Kung；　〃the　opposite　state　should　be　always
  present　to　your　mind。〃＇
  8。　　If　our　expectation　of　advantage　be　tempered　in　this　way；
  we　may　succeed　in　accomplishing　the　essential　part　of　our
  schemes。
  ＇Tu　Mu　says：　　〃If　we　wish　to　wrest　an　advantage　from　the
  enemy；　we　must　not　fix　our　minds　on　that　alone；　but　allow　for　the
  possibility　of　the　enemy　also　doing　some　harm　to　us；　and　let　this
  enter　as　a　factor　into　our　calculations。〃＇
  9。　　If；　on　the　other　hand；　in　the　midst　of　difficulties　we
  are　always　ready　to　seize　an　advantage；　　we　may　extricate
  ourselves　from　misfortune。
  ＇Tu　Mu　says：　　　〃If　I　wish　to　extricate　myself　from　a
  dangerous　position；　I　must　consider　not　only　the　enemy's　ability
  to　injure　me；　but　also　my　own　ability　to　gain　an　advantage　over
  the　enemy。　　If　in　my　counsels　these　two　considerations　are
  properly　blended；　I　shall　succeed　in　liberating　myself。。。。　　For
  instance；　　if　I　am　surrounded　by　the　enemy　and　only　think　of
  effecting　an　escape；　the　nervelessness　of　my　policy　will　incite
  my　adversary　to　pursue　and　crush　me；　it　would　be　far　better　to
  encourage　my　men　to　deliver　a　bold　counter…attack；　and　use　the
  advantage　thus　gained　to　free　myself　from　the　enemy's　toils。〃
  See　the　story　of　Ts‘ao　Ts‘ao；　VII。　ss。　35；　note。＇
  10。　　Reduce　the　hostile　chiefs　by　inflicting　damage　on　them；
  ＇Chia　Lin　enumerates　several　ways　of　inflicting　this　injury；
  some　of　which　would　only　occur　to　the　Oriental　mind：〃Entice
  away　the　enemy's　best　and　wisest　men；　so　that　he　may　be　left
  without　counselors。　　Introduce　traitors　into　his　country；　　that
  the　government　policy　may　be　rendered　futile。　　Foment　intrigue
  and　deceit；　　and　thus　sow　dissension　between　the　ruler　and　his
  ministers。　　　By　means　of　every　artful　　　contrivance；　　　cause
  deterioration　amongst　his　men　and　waste　of　his　treasure。　　Corrupt
  his　morals　by　insidious　gifts　leading　him　into　excess。　　Disturb
  and　unsettle　his　mind　by　presenting　him　with　lovely　women。〃
  Chang　Yu　（after　Wang　Hsi）　makes　a　different　interpretation　of　Sun
  Tzu　here：　　〃Get　the　enemy　into　a　position　where　he　must　suffer
  injury；　and　he　will　submit　of　his　own　accord。〃＇
  and　make　trouble　for　them；
  ＇Tu　Mu；　in　this　phrase；　in　his　interpretation　indicates　that
  trouble　　　should　　　be　make　for　the　　　enemy　　　affecting　　　their
  〃possessions；〃　or；　as　we　might　say；　〃assets；〃　which　he　considers
  to　be　　〃a　large　army；　a　rich　exchequer；　　harmony　amongst　the
  soldiers；　　punctual　fulfillment　of　commands。〃　　These　give　us　a
  whip…hand　over　the　enemy。＇
  and　keep　them　constantly　engaged；
  ＇Literally；　　〃make　servants　of　them。〃　　Tu　Yu　says　　〃prevent
  the　from　having　a