the　preface　to　Pt。　IV。）；　one　and　the　same　action　being　sometimes　good；
  sometimes　bad；　wherefore　to　the　action　which　is　sometimes　bad；　or　arises
  from　some　evil　emotion；　we　may　be　led　by　reason　（IV：xix。）。　Q。E。D。
  Note。…　An　example　will　put　this　point　in　a　clearer　light。　The　action　of
  striking；　in　so　far　as　it　is　considered　physically；　and　in　so　far　as　we
  merely　look　to　the　fact　that　a　man　raises　his　arm；　clenches　his　fist；　and
  moves　his　whole　arm　violently　downwards；　is　a　virtue　or　excellence　which
  is　conceived　as　proper　to　the　structure　of　the　human　body。　If；　then；　a　man；
  moved　by　anger　or　hatred；　is　led　to　clench　his　fist　or　to　move　his　arm；
  this　result　takes　place　（as　we　showed　in　Pt。II。）；　because　one　and　the
  same　action　can　be　associated　with　various　mental　images　of　things；
  therefore　we　may　be　determined　to　the　performance　of　one　and　the　same
  action　by　confused　ideas；　or　by　clear　and　distinct　ideas。　Hence　it　is
  evident　that　every　desire　which　springs　from　emotion；　wherein　the　mind　is
  passive；　would　become　useless；　if　men　could　be　guided　by　reason。　Let　us
  now　see　why　desire　which　arises　from　emotion；　wherein　the　mind　is　passive；
  is　called　by　us　blind。
  Prop。　LX。　Desire　arising　from　a　pleasure
  or　pain；　that　is　not　attributable；　to
  the　whole　body；　but　only　to　one　or　certain
  parts　thereof；　is　without　utility　in
  respect　to　a　man　as　a　whole。
  Proof。…　Let　it　be　assumed；　for　instance；　that　A；　a　part　of　a　body；　is　so
  strengthened　by　some　external　cause；　that　it　prevails　over　the　remaining
  parts　（IV：vi。）。　This　part　will　not　endeavour　to　do　away　with　its　own
  powers；　in　order　that　the　other　parts　of　the　body　may　perform　its　office；
  for　this　it　would　be　necessary　for　it　to　have　a　force　or　power　of　doing
  away　with　its　own　powers；　which　（III：vi。）　is　absurd。　The　said　part；　and；
  consequently；　the　mind　also；　will　endeavour　to　preserve　its　condition。
  Wherefore　desire　arising　from　a　pleasure　of　the　kind　aforesaid　has　no
  utility　in　reference　to　a　man　as　a　whole。　If　it　be　assumed；　on　the　other
  hand；　that　the　part；　A；　be　checked　so　that　the　remaining　parts　prevail；
  it　may　be　proved　in　the　same　manner　that　desire　arising　from　pain　has　no
  utility　in　respect　to　a　man　as　a　whole。　Q。E。D。
  Note。…　As　pleasure　is　generally　（IV：xliv。Note）　attributed　to　one　part
  of　the　body；　we　generally　desire　to　preserve　our　being　with　out　taking
  into　consideration　our　health　as　a　whole：　to　which　it　may　be　added；　that
  the　desires　which　have　most　hold　over　us　（IV：ix。）　take　account　of　the
  present　and　not　of　the　future。
  Prop。　LXI。　Desire　which　springs　from
  reason　cannot　be　excessive。
  Proof。…　Desire　（Def。　of　the　Emotions：i。）　considered　absolutely　is　the
  actual　essence　of　man；　in　so　far　as　it　is　conceived　as　in　any　way
  determined　to　a　particular　activity　by　some　given　modification　of　itself。
  Hence　desire；　which　arises　from　reason；　that　is　（III：iii。）；　which　is
  engendered　in　us　in　so　far　as　we　act；　is　the　actual　essence　or　nature　of
  man；　in　so　far　as　it　is　conceived　as　determined　to　such　activities　as　are
  adequately　conceived　through　man's　essence　only　（III：Def。ii。）。　Now；　if
  such　desire　could　be　excessive；　human　nature　considered　in　itself　alone
  would　be　able　to　exceed　itself；　or　would　be　able　to　do　more　than　it　can；
  a　manifest　contradiction。　Therefore；　such　desire　cannot　be　excessive。　Q。E。D。
  Prop。　LXII。　In　so　far　as　the　mind　conceives
  a　thing　under　the　dictates　of　reason；　it　is
  affected　equally；　whether　the　idea　be　of　a
  thing　future；　past；　or　present。
  Proof。…　Whatsoever　the　mind　conceives　under　the　guidance　of　reason；　it
  conceives　under　the　form　of　eternity　or　necessity　（II：xliv。Coroll。ii。）；
  and　is　therefore　affected　with　the　same　certitude　（II：xliii。&Note）。
  Wherefore；　whether　the　thing　be　present；　past；　or　future；　the　mind
  conceives　it　under　the　same　necessity　and　is　affected　with　the　same
  certitude；　and　whether　the　idea　be　of　something　present；　past；　or　future；
  it　will　in　all　cases　be　equally　true　（II：xli。）；　that　is；　it　will　always
  possess　the　same　properties　of　an　adequate　idea　（II：Def。iv。）；　therefore；　in
  so　far　as　the　mind　conceives　things　under　the　dictates　of　reason；　it　is
  affected　in　the　same　manner；　whether　the　idea　be　of　a　thing　future；　past；
  or　present。　Q。E。D。
  Note。…　If　we　could　possess　an　adequate　knowledge　of　the　duration　of　things；
  and　could　determine　by　reason　their　periods　of　existence；　we　should
  contemplate　things　future　with　the　same　emotion　as　things　present；　and
  the　mind　would　desire　as　though　it　were　present　the　good　which　it
  conceived　as　future；　consequently　it　would　necessarily　neglect　a　lesser
  good　in　the　present　for　the　sake　of　a　greater　good　in　the　future；　and
  would　in　no　wise　desire　that　which　is　good　in　the　present　but　a　source　of
  evil　in　the　future；　as　we　shall　presently　show。　However；　we　can　have　but
  a　very　inadequate　knowledge　of　the　duration　of　things　（II：xxxi。）　and　the
  periods　of　their　existence　（II：xliv。Note）　we　can　only　determine　by
  imagination；　which　is　not　so　powerfully　affected　by　the　future　as　by　the
  present。　Hence　such　true　knowledge　of　good　and　evil　as　we　possess　is
  merely　abstract　or　general；　and　the　judgment　which　we　pass　on　the　order
  of　things　and　the　connection　of　causes；　with　a　view　to　determining　what
  is　good　or　bad　for　us　in　the；　present；　is　rather　imaginary　than　real。
  Therefore　it　is　nothing　wonderful；　if　the　desire　arising　from　such
  knowledge　of　good　and　evil；　in　so　far　as　it　looks　on　into　the　future；　be
  more　readily　checked　than　the　desire　of　things　which　are　agreeable　at　the
  present　time。　（Cf。　IV：xvi。）
  Prop。　LXIII。　He　who　is　led　by　fear；
  and　does　good　in　order　to　escape　evil；
  is　not　led　by　reason。
  Proof。…　All　the　emotions　which　are　attributable　to　the　mind　as　active；
  or　in　other　words　to　reason；　are　emotions　of　pleasure　and　desire　（III：lix。）；
  therefore；　he　who　is　led　by　fear；　and　does　good　in　order　to　escape　evil；
  is　not　led　by　reason。
  Note。…　Superstitions　persons；　who　know　better　how　to　rail　at　vice　than
  how　to　teach　virtue；　and　who　strive　not　to　guide　men　by　reason；　but　so
  to　restrain　them　that　they　would　rather　escape　evil　than　love　virtue；
  have　no　other　aim　but　to　make　others　as　wretched　as　themselves；　wherefore
  it　is　nothing　wonderful；　if　they　be　generally　troublesome　and　odious　to
  their　fellow…men。
  Corollary。…　Under　desire　which　springs　from　reason；　we　seek　good　directly；
  and　shun　evil　indirectly。
  Proof。…　Desire　which　springs　from　reason　can　only　spring　from　a　pleasurable
  emotion；　wherein　the　mind　is　not　passive　（III：lix。）；　in　other　words；　from
  a　pleasure　which　cannot　be　excessive　（IV：lxi。）；　and　not　from　pain；
  wherefore　this　desire　springs　from　the　knowledge　of　good；　not　of　evil
  （IV：viii。）；　hence　under　the　guidance　of　reason　we　seek　good　directly　and
  only　by　implication　shun　evil。　Q。E。D。
  Note。…　This　Corollary　may　be　illustrated　by　the　example　of　a　sick　and　a
  healthy　man。　The　sick　man　through　fear　of　death　eats　what　he　naturally
  shrinks　from；　but　the　healthy　man　takes　pleasure　in　his　food；　and　thus
  gets　a　better　enjoyment　out　of　life；　than　if　he　were　in　fear　of　death；
  and　desired　directly　to　avoid　it。　So　a　judge；　who　condemns　a　criminal
  to　death；　not　from　hatred　or　anger　but　from　love　of　the　public
  well…being；　is　guided　solely　by　reason。
  Prop。　LXIV。　The　knowledge　of　evil　is
  an　inadequate　knowledge。
  Proof。…　The　knowledge　of　evil　（IV：viii。）　is　pain；　in　so　far　as　we　are
  conscious　thereof。　Now　pain　is　the　transition　to　a　lesser　perfection
  （Def。　of　the　Emotions：iii。）　and　therefore　cannot　be　understood　through
  man's　nature　（III：vi。；&　II：vii。）；　therefore　it　is　a　passive　state
  （III。Def。ii。）　which　（III：iii。）　depends　on　inadequate　ideas；　consequently
  the　knowledge　thereof　（II：xxix。）；　namely；　the　knowledge　of　evil；　is
  inadequate。　Q。E。D。
  Corollary。…　Hence　it　follows　that；　if　the　human　mind　possessed　only
  adequate　ideas；　it　would　form　no　conception　of　evil。
  Prop。　LXV。　Under　the　guidance　of　reason　we
  should　pursue　the　greater　of　two　goods　and
  the　lesser　of　two　evils。
  Proof。…　A　good　which　prevents　our　enjoyment　of　a　greater　good　is　in
  reality　an　evil；　for　we　apply　the　terms　good　and　bad　to　things；　in　so
  far　as　we　compare　them　one　with　another　（see　preface　to　this　Part）；
  therefore；　evil　is　in　reality　a　lesser　good；　hence　under　the　guidance　of
  reason　we　seek　or　pursue　only　the　greater　good　and　the　lesser　evil。　Q。E。D。
  Corollary。…　We　may；　under　the　guidance　of　reason；　pursue　the　lesser　evil
  as