ON　LONGEVITY　AND　SHORTNESS　OF　LIFE
  by　Aristotle
  translated　by　G。　R。　T。　Ross
  1
  THE　reasons　for　some　animals　being　long…lived　and　others
  short…lived；　and；　in　a　word；　causes　of　the　length　and　brevity　of
  life　call　for　investigation。
  The　necessary　beginning　to　our　inquiry　is　a　statement　of　the
  difficulties　about　these　points。　For　it　is　not　clear　whether　in
  animals　and　plants　universally　it　is　a　single　or　diverse　cause　that
  makes　some　to　be　long…lived；　others　short…lived。　Plants　too　have　in
  some　cases　a　long　life；　while　in　others　it　lasts　but　for　a　year。
  Further；　in　a　natural　structure　are　longevity　and　a　sound
  constitution　coincident；　or　is　shortness　of　life　independent　of
  unhealthiness？　Perhaps　in　the　case　of　certain　maladies　a　diseased
  state　of　the　body　and　shortness　of　life　are　interchangeable；　while
  in　the　case　of　others　ill…health　is　perfectly　compatible　with　long
  life。
  Of　sleep　and　waking　we　have　already　treated；　about　life　and　death　we
  shall　speak　later　on；　and　likewise　about　health　and　disease；　in　so　far
  as　it　belongs　to　the　science　of　nature　to　do　so。　But　at　present　we
  have　to　investigate　the　causes　of　some　creatures　being　long…lived；　and
  others　short…lived。　We　find　this　distinction　affecting　not　only　entire
  genera　opposed　as　wholes　to　one　another；　but　applying　also　to
  contrasted　sets　of　individuals　within　the　same　species。　As　an　instance
  of　the　difference　applying　to　the　genus　I　give　man　and　horse　（for
  mankind　has　a　longer　life　than　the　horse）；　while　within　the　species
  there　is　the　difference　between　man　and　man；　for　of　men　also　some
  are　long…lived；　others　short…lived；　differing　from　each　other　in
  respect　of　the　different　regions　in　which　they　dwell。　Races　inhabiting
  warm　countries　have　longer　life；　those　living　in　a　cold　climate　live　a
  shorter　time。　Likewise　there　are　similar　differences　among　individuals
  occupying　the　same　locality。
  2
  In　order　to　find　premisses　for　our　argument；　we　must　answer　the
  question；　What　is　that　which；　in　natural　objects；　makes　them　easily
  destroyed；　or　the　reverse？　Since　fire　and　water；　and　whatsoever　is
  akin　thereto；　do　not　possess　identical　powers　they　are　reciprocal
  causes　of　generation　and　decay。　Hence　it　is　natural　to　infer　that
  everything　else　arising　from　them　and　composed　of　them　should　share　in
  the　same　nature；　in　all　cases　where　things　are　not；　like　a　house；　a
  composite　unity　formed　by　the　synthesis　of　many　things。
  In　other　matters　a　different　account　must　be　given；　for　in　many
  things　their　mode　of　dissolution　is　something　peculiar　to
  themselves；　e。g。　in　knowledge　and　health　and　disease。　These　pass
  away　even　though　the　medium　in　which　they　are　found　is　not　destroyed
  but　continues　to　exist；　for　example；　take　the　termination　of
  ignorance；　which　is　recollection　or　learning；　while　knowledge　passes
  away　into　forgetfulness；　or　error。　But　accidentally　the　disintegration
  of　a　natural　object　is　accompanied　by　the　destruction　of　the
  non…physical　reality；　for；　when　the　animal　dies；　the　health　or
  knowledge　resident　in　it　passes　away　too。　Hence　from　these
  considerations　we　may　draw　a　conclusion　about　the　soul　too；　for；　if
  the　inherence　of　soul　in　body　is　not　a　matter　of　nature　but　like
  that　of　knowledge　in　the　soul；　there　would　be　another　mode　of
  dissolution　pertaining　to　it　besides　that　which　occurs　when　the　body
  is　destroyed。　But　since　evidently　it　does　not　admit　of　this　dual
  dissolution；　the　soul　must　stand　in　a　different　case　in　respect　of　its
  union　with　the　body。
  3
  Perhaps　one　might　reasonably　raise　the　question　whether　there　is　any
  place　where　what　is　corruptible　becomes　incorruptible；　as　fire　does　in
  the　upper　regions　where　it　meets　with　no　opposite。　Opposites　destroy
  each　other；　and　hence　accidentally；　by　their　destruction；　whatsoever
  is　attributed　to　them　is　destroyed。　But　no　opposite　in　a　real
  substance　is　accidentally　destroyed；　because　real　substance　is　not
  predicated　of　any　subject。　Hence　a　thing　which　has　no　opposite；　or
  which　is　situated　where　it　has　no　opposite；　cannot　be　destroyed。　For
  what　will　that　be　which　can　destroy　it；　if　destruction　comes　only
  through　contraries；　but　no　contrary　to　it　exists　either　absolutely
  or　in　the　particular　place　where　it　is？　But　perhaps　this　is　in　one
  sense　true；　in　another　sense　not　true；　for　it　is　impossible　that
  anything　containing　matter　should　not　have　in　any　sense　an　opposite。
  Heat　and　straightness　can　be　present　in　every　part　of　a　thing；　but
  it　is　impossible　that　the　thing　should　be　nothing　but　hot　or　white
  or　straight；　for；　if　that　were　so；　attributes　would　have　an
  independent　existence。　Hence　if；　in　all　cases；　whenever　the　active　and
  the　passive　exist　together；　the　one　acts　and　the　other　is　acted　on；　it
  is　impossible　that　no　change　should　occur。　Further；　this　is　so　if　a
  waste　product　is　an　opposite；　and　waste　must　always　be　produced；　for
  opposition　is　always　the　source　of　change；　and　refuse　is　what
  remains　of　the　previous　opposite。　But；　after　expelling　everything　of　a
  nature　actually　opposed；　would　an　object　in　this　case　also　be
  imperishable？　No；　it　would　be　destroyed　by　the　environment。
  If　then　that　is　so；　what　we　have　said　sufficiently　accounts　for
  the　change；　but；　if　not；　we　must　assume　that　something　of　actually
  opposite　character　is　in　the　changing　object；　and　refuse　is　produced。
  Hence　accidentally　a　lesser　flame　is　consumed　by　a　greater　one；
  for　the　nutriment；　to　wit　the　smoke；　which　the　former　takes　a　long
  period　to　expend；　is　used　up　by　the　big　flame　quickly。
  Hence　＇too＇　all　things　are　at　all　times　in　a　state　of　transition　and
  are　coming　into　being　and　passing　away。　The　environment　acts　on　them
  either　favourably　or　antagonistically；　and；　owing　to　this；　things　that
  change　their　situation　become　more　or　less　enduring　than　their
  nature　warrants；　but　never　are　they　eternal　when　they　contain　contrary
  qualities；　for　their　matter　is　an　immediate　source　of　contrariety；
  so　that　if　it　involves　locality　they　show　change　of　situation；　if
  quantity；　increase　and　diminution；　while　if　it　involves　qualitative
  affection　we　find　alteration　of　character。
  4
  We　find　that　a　superior　immunity　from　decay　attaches　neither　to
  the　largest　animals　（the　horse　has　shorter　life　than　man）　nor　to　those
  that　are　small　（for　most　insects　live　but　for　a　year）。　Nor　are
  plants　as　a　whole　less　liable　to　perish　than　animals　（many　plants
  are　annuals）；　nor　have　sanguineous　animals　the　pre…eminence　（for　the
  bee　is　longer…lived　than　certain　sanguineous　animals）。　Neither　is　it
  the　bloodless　animals　that　live　longest　（for　molluscs　live　only　a
  year；　though　bloodless）；　nor　terrestrial　organisms　（there　are　both
  plants　and　terrestrial　animals　of　which　a　single　year　is　the
  period）；　nor　the　occupants　of　the　sea　（for　there　we　find　the
  crustaceans　and　the　molluscs；　which　are　short…lived）。
  Speaking　generally；　the　longest…lived　things　occur　among　the　plants；
  e。g。　the　date…palm。　Next　in　order　we　find　them　among　the　sanguineous
  animals　rather　than　among　the　bloodless；　and　among　those　with　feet
  rather　than　among　the　denizens　of　the　water。　Hence；　taking　these　two
  characters　together；　the　longest…lived　animals　fall　among
  sanguineous　animals　which　have　feet；　e。g。　man　and　elephant。　As　a
  matter　of　fact　also　it　is　a　general　rule　that　the　larger　live　longer
  than　the　smaller；　for　the　other　long…lived　animals　too　happen　to　be　of
  a　large　size；　as　are　also　those　I　have　mentioned。
  5
  The　following　considerations　may　enable　us　to　understand　the　reasons
  for　all　these　facts。　We　must　remember　that　an　animal　is　by　nature
  humid　and　warm；　and　to　live　is　to　be　of　such　a　constitution；　while　old
  age　is　dry　and　cold；　and　so　is　a　corpse。　This　is　plain　to　observation。
  But　the　material　constituting　the　bodies　of　all　things　consists　of　the
  following…the　hot　and　the　cold；　the　dry　and　the　moist。　Hence　when　they
  age　they　must　become　dry；　and　therefore　the　fluid　in　them　requires
  to　be　not　easily　dried　up。　Thus　we　explain　why　fat　things　are　not
  liable　to　decay。　The　reason　is　that　they　contain　air；　now　air
  relatively　to　the　other　elements　is　fire；　and　fire　never　becomes
  corrupted。
  Again　the　humid　element　in　animals　must　not　be　small　in　quantity；
  for　a　small　quantity　is　easily　dried　up。　This　is　why　both　plants　and
  animals　that　are　large　are；　as　a　general　rule；　longer…lived　than　the
  rest；　as　was　said　before；　it　is　to　be　expected　that　the　larger
  sh