But　consider　the　sweet　as　beneficial；　the　bitter　as　injurious：　then　bitter　and　sweet　are　distinguished；　not　by　Quality；　but　by　Relation。　We　might　also　be　disposed　to　identify　the　sweet　with　the　thick；　and　the　Pungent　with　the　thin：　〃thick〃　however　hardly　reveals　the　essence　but　merely　the　cause　of　sweetness…　an　argument　which　applies　equally　to　pungency。　　　　　We　must　therefore　reflect　whether　it　may　be　taken　as　an　invariable　rule　that　Quality　is　never　a　differentia　of　Quality；　any　more　than　Substance　is　a　differentia　of　Substance；　or　Quantity　of　Quantity。　　　　　Surely；　it　may　be　interposed；　five　differs　from　three　by　two。　No：　it　exceeds　it　by　two；　we　do　not　say　that　it　differs：　how　could　it　differ　by　a　〃two〃　in　the　〃three〃？　We　may　add　that　neither　can　Motion　differ　from　Motion　by　Motion。　There　is；　in　short；　no　parallel　in　any　of　the　other　genera。　　　　　In　the　case　of　virtue　and　vice；　whole　must　be　compared　with　whole；　and　the　differentiation　conducted　on　this　basis。　As　for　the　differentia　being　derived　from　the　same　genus　as　themselves；　namely；　Quality；　and　from　no　other　genus；　if　we　proceed　on　the　principle　that　virtue　is　bound　up　with　pleasure；　vice　with　lust；　virtue　again　with　the　acquisition　of　food；　vice　with　idle　extravagance；　and　accept　these　definitions　as　satisfactory；　then　clearly　we　have；　here　too；　differentiae　which　are　not　qualities。　　　　　19。　With　Quality　we　have　undertaken　to　group　the　dependent　qualia；　in　so　far　as　Quality　is　bound　up　with　them；　we　shall　not　however　introduce　into　this　category　the　qualified　objects　＇qua　objects＇；　that　we　may　not　be　dealing　with　two　categories　at　once；　we　shall　pass　over　the　objects　to　that　which　gives　them　their　＇specific＇　name。　　　　　But　how　are　we　to　classify　such　terms　as　〃not　white〃？　If　〃not　white〃　signifies　some　other　colour；　it　is　a　quality。　But　if　it　is　merely　a　negation　of　an　enumeration　of　things　not　white；　it　will　be　either　a　meaningless　sound；　or　else　a　name　or　definition　of　something　actual：　if　a　sound；　it　is　a　kind　of　motion；　if　a　name　or　definition；　it　is　a　relative；　inasmuch　as　names　and　definitions　are　significant。　But　if　not　only　the　things　enumerated　are　in　some　one　genus；　but　also　the　propositions　and　terms　in　question　must　be　each　of　them　significative　of　some　genus；　then　we　shall　assert　that　negative　propositions　and　terms　posit　certain　things　within　a　restricted　field　and　deny　others。　Perhaps；　however；　it　would　be　better；　in　view　of　their　composite　nature；　not　to　include　the　negations　in　the　same　genus　as　the　affirmations。　　　　　What　view；　then；　shall　we　take　of　privations？　If　they　are　privations　of　qualities；　they　will　themselves　be　qualities：　〃toothless〃　and　〃blind；〃　for　example；　are　qualities。　〃Naked〃　and　〃dothed；〃　on　the　other　hand；　are　neither　of　them　qualities　but　states：　they　therefore　comport　a　relation　to　something　else。　　　　　＇With　regard　to　passive　qualities：＇　　　　　Passivity；　while　it　lasts；　is　not　a　quality　but　a　motion；　when　it　is　a　past　experience　remaining　in　one's　possession；　it　is　a　quality；　if　one　ceases　to　possess　the　experience　then　regarded　as　a　finished　occurrence；　one　is　considered　to　have　been　moved…　in　other　words；　to　have　been　in　Motion。　But　in　none　of　these　cases　is　it　necessary　to　conceive　of　anything　but　Motion；　the　idea　of　time　should　be　excluded；　even　present　time　has　no　right　to　be　introduced。　　　　　〃Well〃　and　similar　adverbial　expressions　are　to　be　referred　to　the　single　generic　notion　＇of　Quality＇。　　　　　It　remains　to　consider　whether　blushing　should　be　referred　to　Quality；　even　though　the　person　blushing　is　not　included　in　this　category。　The　fact　of　becoming　flushed　is　rightly　not　referred　to　Quality；　for　it　involves　passivity…　in　short；　Motion。　But　if　one　has　ceased　to　become　flushed　and　is　actually　red；　this　is　surely　a　case　of　Quality；　which　is　independent　of　time。　How　indeed　are　we　to　define　Quality　but　by　the　aspect　which　a　substance　presents？　By　predicating　of　a　man　redness；　we　clearly　ascribe　to　him　a　quality。　　　　　We　shall　accordingly　maintain　that　states　alone；　and　not　dispositions；　constitute　qualities：　thus；　〃hot〃　is　a　quality　but　not　〃growing　hot；〃　〃ill〃　but　not　〃turning　ill。〃　　　　　20。　We　have　to　ascertain　whether　there　is　not　to　every　quality　a　contrary。　In　the　case　of　virtue　and　vice；　even　the　mean　appears　to　be　contrary　to　the　extremes。　　　　　But　when　we　turn　to　colours；　we　do　not　find　the　intermediates　so　related。　If　we　regard　the　intermediates　as　blendings　of　the　extremes；　we　must　not　posit　any　contrariety　other　than　that　between　black　and　white；　but　must　show　that　all　other　colours　are　combinations　of　these　two。　Contrariety　however　demands　that　there　be　some　one　distinct　quality　in　the　intermediates；　though　this　quality　may　be　seen　to　arise　from　a　combination。　　　　　It　may　further　be　suggested　that　contraries　not　only　differ　from　each　other；　but　also　entail　the　greatest　possible　difference。　But　〃the　greatest　possible　difference〃　would　seem　to　presuppose　that　intermediates　have　already　been　established：　eliminate　the　series；　and　how　will　you　define　〃the　greatest　possible〃？　Sight；　we　may　be　told；　will　reveal　to　us　that　grey　is　nearer　than　black　to　white；　and　taste　may　be　our　judge　when　we　have　hot；　cold　and　no　intermediate。　　　　　That　we　are　accustomed　to　act　upon　these　assumptions　is　obvious　enough；　but　the　following　considerations　may　perhaps　commend　themselves：　　　　　White　and　yellow　are　entirely　different　from　each　other…　a　statement　which　applies　to　any　colour　whatsoever　as　compared　with　any　other；　they　are　accordingly　contrary　qualities。　Their　contrariety　is　independent　of　the　presence　of　intermediates：　between　health　and　disease　no　intermediate　intrudes；　and　yet　they　are　contraries。　　　　　It　may　be　urged　that　the　products　of　a　contrariety　exhibit　the　greatest　diversity。　But　〃the　greatest　diversity〃　is　clearly　meaningless；　unless　we　can　point　to　lower　degrees　of　diversity　in　the　means。　Thus；　we　cannot　speak　of　〃the　greatest　diversity〃　in　reference　to　health　and　disease。　This　definition　of　contrariety　is　therefore　inadmissible。　　　　　Suppose　that　we　say　〃great　diversity〃　instead　of　〃the　greatest〃：　if　〃great〃　is　equivalent　to　greater　and　implies　a　less；　immediate　contraries　will　again　escape　us；　if；　on　the　other　hand；　we　mean　strictly　〃great〃　and　assume　that　every　quality　shows　a　great　divergence　from　every　other；　we　must　not　suppose　that　the　divergence　can　be　measured　by　a　comparative。　　　　　Nonetheless；　we　must　endeavour　to　find　a　meaning　for　the　term　〃contrary。〃　Can　we　accept　the　principle　that　when　things　have　a　certain　similarity　which　is　not　generic　nor　in　any　sense　due　to　admixture；　but　a　similarity　residing　in　their　forms…　if　the　term　be　permitted…　they　differ　in　degree　but　are　not　contraries；　contraries　being　rather　those　things　which　have　no　specific　identity？　It　would　be　necessary　to　stipulate　that　they　belong　to　the　same　genus；　Quality；　in　order　to　cover　those　immediate　contraries　which　＇apparently＇　have　nothing　conducing　to　similarity；　inasmuch　as　there　are　no　intermediates　looking　both　ways；　as　it　were；　and　having　a　mutual　similarity　to　each　other；　some　contraries　are　precluded　by　their　isolation　from　similarity。　　　　　If　these　observations　be　sound；　colours　which　have　a　common　ground　will　not　be　contraries。　But　there　will　be　nothing　to　prevent；　not　indeed　every　colour　from　being　contrary　to　every　other；　but　any　one　colour　from　being　contrary　to　any　other；　and　similarly　with　tastes。　This　will　serve　as　a　statement　of　the　problem。　　　　　As　for　Degree　＇subsisting　in　Quality＇；　it　was　given　as　our　opinion　that　it　exists　in　the　objects　participating　in　Quality；　though　whether　it　enters　into　qualities　as　such…　into　health　and　justice…　was　left　open　to　question。　If　indeed　these　qualities　possess　an　extension　quite　apart　from　their　participants；　we　must　actually　ascribe　to　them　degrees：　but　in　truth　they　belong　to　a　sphere　where　each　entity　is　the　whole　and　does　not　admit　of　degree。　　　　　21。　The　claim　of　Motion　to　be　established　as　a　genus　will　depend　upon　three　conditions：　first；　that　it　cannot　rightly　be　referred　to　any　other　genus；　second；　that　nothing　higher　than　itself　can　be　predicated　of　it　in　respect　of　its　essence；　third；　that　by　assuming　differences　it　will　produce　species。　These　conditions　satisfied；　we　may　consider　the　nature　of　the　genus　to　which　we　shall　refer　it。　　　　　Clearly　it　cannot　be　identified　with　either　the　Substance　or　the　Quality　of　the　things　which　possess　it。　It　cannot；　further；　be　consigned　to　Action；　for　Passivity　also　comprises　a　variety　of　motions；　nor　again　to　Passivity　itself；　because　many　motions　are　actions：　on　the　contrary；　actions　and　passions　are　to　be　referred　to　Motion。　　　　　Furthermore；　it　cannot　lay　claim　to　the　category　of　Relation　on　the　mere　ground　that　it　has　an　attributive　and　not　a　self…centred　existence：　on　this　ground；　Quality　too　would　find　itself　in　that　same　category；　for　Quality　is　an　attribute　and　contained　in　an　external：　and　the　same　is　true　of　Quantity。　　　　　If　we　are　agreed　that　Quality　and　Quantity；　though　attributive；　are　real　entities；　and　on　the　basis　of　this　reality　distinguishable　as　Quality　and　Quantity　respectively：　then；　on　the　same　principle；　since　Motion；　though　an　attribute　has　a　reality　prior　to　its　attribution；　it　is　incumbent　upon　us　to　discover　the　intrinsic　nature　of　thi