is　the　same　thing）　in　so　far　as　it　reasons。　Therefore　we　know　nothing
  to　be　good　or　evil　save　such　things　as　really　conduce；　&c。　Q。E。D。
  Prop。　XXVIII。　The　mind's　highest　good　is
  the　knowledge　of　God；　and　the　mind's
  highest　virtue　is　to　know　God。
  Proof。…　The　mind　is　not　capable　of　understanding　anything　higher　than　God；
  that　is　（I：Def。vi。）；　than　a　Being　absolutely　infinite；　and　without　which
  （I：xv。）　nothing　can　either　be　or　be　conceived；　therefore　（IV：xxvi。；
  &xxvii。）；　the　mind's　highest　utility　or　（IV：Def。i。）　good　is　the　knowledge
  of　God。　Again；　the　mind　is　active；　only　in　so　far　as　it　understands；　and
  only　to　the　same　extent　can　it　be　said　absolutely　to　act　virtuously。　The
  mind's　absolute　virtue　is　therefore　to　understand。　Now；　as　we　have　already
  shown；　the　highest　that　the　mind　can　understand　is　God；　therefore　the
  highest　virtue　of　the　mind　is　to　understand　or　to　know　God。　Q。E。D。
  Prop。　XXIX。　No　individual　thing；　which　is
  entirely　different　from　our　own　nature；
  can　help　or　check　our　power　of　activity；　and
  absolutely　nothing　can　do　us　good　or　harm；
  unless　it　has　something　in　common　with　our　nature。
  Proof。…　The　power　of　every　individual　thing；　and　consequently　the　power　of
  man；　whereby　he　exists　and　operates；　can　only　be　determined　by　an
  individual　thing　（I：xxviii。）；　whose　nature　（II：vi。）　must　be　understood
  through　the　same　nature　as　that；　through　which　human　nature　is　conceived。
  Therefore　our　power　of　activity；　however　it　be　conceived；　can　be　determined
  and　consequently　helped　or　hindered　by　the　power　of　any　other　individual
  thing；　which　has　something　in　common　with　us；　but　not　by　the　power　of
  anything；　of　which　the　nature　is　entirely　different　from　our　own；　and
  since　we　call　good　or　evil　that　which　is　the　cause　of　pleasure　or　pain
  （IV：viii。）；　that　is　（III：xi。Note）；　which　increases　or　diminishes；　helps
  or　hinders；　our　power　of　activity；　therefore；　that　which　is　entirely；
  different　from　our　nature　can　neither　be　to　us　good　nor　bad。　Q。E。D。
  Prop。　XXX。　A　thing　cannot　be　bad　for　us
  through　the　quality　which　it　has　in　common
  with　our　nature；　but　it　is　bad　for　us　in　so
  far　as　it　is　contrary　to　our　nature。
  Proof。…　We　call　a　thing　bad　when　it　is　the　cause　of　pain　（IV：viii。）；　that
  is　（by　the　Def。；　which　see　in　III：xi。Note）；　when　it　diminishes　or　checks
  our　power　of　action。　Therefore；　if　anything　were　bad　for　us　through　that
  quality　which　it　has　in　common　with　our　nature；　it　would　be　able
  itself　to　diminish　or　check　that　which　it　has　in　common　with　our　nature；
  which　（III：iv。）　is　absurd。　Wherefore　nothing　can　be　bad　for　us　through
  that　quality　which　it　has　in　common　with　us；　but；　on　the　other　hand；　in
  so　far　as　it　is　bad　for　us；　that　is　（as　we　have　just　shown）；　in　so　far　as
  it　can　diminish　or　check　our　power　of　action；　it　is　contrary　to　our　nature。
  Q。E。D。
  Prop。　XXXI。　In　so　far　as　a　thing　is　in　harmony
  with　our　nature；　it　is　necessarily　good。
  Proof。…　In　so　far　as　a　thing　is　in　harmony　with　our　nature；　it　cannot　be
  bad　for　it。　It　will　therefore　necessarily　be　either　good　or　indifferent。
  If　it　be　assumed　that　it　be　neither　good　nor　bad；　nothing　will　follow　from
  its　nature　（IV：Def。i。）；　which　tends　to　the　preservation　of　our　nature；
  that　is　（by　the　hypothesis）；　which　tends　to　the　preservation　of　the　thing
  itself；　but　this　（III：vi。）　is　absurd；　therefore；　in　so　far　as　a　thing　is
  in　harmony　with　our　nature；　it　is　necessarily　good。　Q。E。D。
  Corollary。…　Hence　it　follows；　that；　in　proportion　as　a　thing　is　in　harmony
  with　our　nature；　so　is　it　more　useful　or　better　for　us；　and　vice　versa；　in
  proportion　as　a　thing　is　more　useful　for　us；　so　is　it　more　in　harmony　with
  our　nature。　For；　in　so　far　as　it　is　not　in　harmony　with　our　nature；　it
  will　necessarily　be　different　therefrom　or　contrary　thereto。　If　different；
  it　can　neither　be　good　nor　bad　（IV：xxix。）；　if　contrary；　it　will　be　contrary
  to　that　which　is　in　harmony　with　our　nature；　that　is；　contrary　to　what　is
  good　…　in　short；　bad。　Nothing；　therefore；　can　be　good；　except　in　so　far　as
  it　is　in　harmony　with　our　nature；　and　hence　a　thing　is　useful；　in　proportion
  as　it　is　in　harmony　with　our　nature；　and　vice　versa。　Q。E。D。
  Prop。　XXXII。　In　so　far　as　men　are　a　prey
  to　passion；　they　cannot；　in　that　respect；
  be　said　to　be　naturally　in　harmony。
  Proof。　Things；　which　are　said　to　be　in　harmony　naturally；　are　understood　to
  agree　in　power　（III：vii。）；　not　in　want　of　power　or　negation；　and
  consequently　not　in　passion　（III：iii。Note）；　wherefore　men；　in　so　far　as
  they　are　a　prey　to　their　passions；　cannot　be　said　to　be　naturally　in
  harmony。　Q。E。D。
  Note。…　This　is　also　self…evident；　for；　if　we　say　that　white　and　black　only
  agree　in　the　fact　that　neither　is　red；　we　absolutely　affirm　that　the　do　not
  agree　in　any　respect。　So；　if　we　say　that　a　man　and　a　stone　only　agree　in　the
  fact　that　both　are　finite　…　wanting　in　power；　not　existing　by　the　necessity
  of　their　own　nature；　or；　lastly；　indefinitely　surpassed　by　the　power　of
  external　causes　…　we　should　certainly　affirm　that　a　man　and　a　stone　are　in
  no　respect　alike；　therefore；　things　which　agree　only　in　negation；　or　in
  qualities　which　neither　possess；　really　agree　in　no　respect。
  Prop。　XXXIII。　Men　can　differ　in　nature；
  in　so　far　as　they　are　assailed　by　those
  emotions；　which　are　passions；　or　passive
  states；　and　to　this　extent　one　and　the
  same　man　is　variable　and　inconstant。
  Proof。…　The　nature　or　essence　of　the　emotions　cannot　be　explained　solely
  through　our　essence　or　nature　（III：Def。i。&ii。）；　but　it　must　be　defined　by
  the　power；　that　is　（III：vii。）；　by　the　nature　of　external　causes　in
  comparison　with　our　own；　hence　it　follows；　that　there　are　as　many　kinds　of
  each　emotion　as　there　are　external　objects　whereby　we　are　affected
  （III：lvi。）；　and　that　men　may　be　differently　affected　by　one　and　the　same
  object　（III：li）；　and　to　this　extent　differ　in　nature；　lastly；　that　one　and
  the　same　man　may　be　differently　affected　towards　the　same　object；　and　may
  therefore　be　variable　and　inconstant。　Q。E。D。
  Prop。　XXXIV。　In　so　far　as　men　are　assailed
  by　emotions　which　are　passions；　they　can　be
  contrary　one　to　another。
  Proof。…　A　man；　for　instance　Peter；　can　be　the　cause　of　Paul's　feeling　pain；
  because　he　（Peter）　possesses　something　similar　to　that　which　Paul　hates
  （III：xvi。）；　or　because　Peter　has　sole　possession　of　a　thing　which　Paul　also
  loves　（III：xxxii。&Note）；　or　for　other　causes　（of　which　the　chief　are
  enumerated　in　III：lv。Note）　；　it　may　therefore　happen　that　Paul　should　hate
  Peter　（Def。　of　Emotions：　vii。）；　consequently　it　may　easily　happen　also；　that
  Peter　should　hate　Paul　in　return；　and　that　each　should　endeavour　to　do　the
  other　an　injury；　（III：xxxix。）；　that　is　（IV：xxx。）；　that　they　should　be
  contrary　one　to　another。　But　the　emotion　of　pain　is　always　a　passion
  or　passive　state　（III：lix。）；　hence　men；　in　so　far　as　they　are　assailed　by
  emotions　which　are　passions；　can　be　contrary　one　to　another。　Q。E。D。
  Note。…　I　said　that　Paul　may　hate　Peter；　because　he　conceives　that　Peter
  possesses　something　which　he　（Paul）　also　loves；　from　this　it　seems；　at　first
  sight；　to　follow；　that　these　two　men；　through　both　loving　the　same　thing；
  and；　consequently；　through　agreement　of　their　respective　natures；　stand　in
  one　another's　way；　if　this　were　so；　II：xxx。　and　II：xxxi。　would　be　untrue。
  But　if　we　give　the　matter　our　unbiased　attention；　we　shall　see　that　the
  discrepancy　vanishes。　For　the　two　men　are　not　in　one　another's　way　in
  virtue　of　the　agreement　of　their　natures；　that　is；　through　both　loving　the
  same　thing；　but　in　virtue　of　one　differing　from　the　other。　For；　in　so　far
  as　each　loves　the　same　thing；　the　love　of　each　is　fostered　thereby
  （III：xxxi。）；　that　is　（Def。　of　the　Emotions：　vi。）　the　pleasure　of　each　is
  fostered　thereby。　Wherefore　it　is　far　from　being　the　case；　that　they　are
  at　variance　through　both　loving　the　same　thing；　and　through　the　agreement
  in　their　natures。　The　cause　for　their　opposition　lies；　as　I　have　said；
  solely　in　the　fact　that　they　are　assumed　to　differ。　For　we　assume　that
  Peter　has　the　idea　of　the　loved　object　as　already　in　his　possession；　while
  Paul　has　the　idea　of　the　loved　object　as　lost。　Hence　the　one　man　will　be
  affected　with　pleasure；　the　other　will　be　affected　with　pain；　and　thus　they
  will　be　at　variance　one　with　another。　We　can　easily　show　in　like　manner；
  that　all　other　causes　of　hatred　depend　solely　on　differences；　and　not　on
  the　agreement　between　men's　natures。
  Prop。　XX