, ▁mobile ▁perspective ", ▁and ▁the ▁" mix ing ... ▁of ▁the ▁success ive ▁and ▁the ▁simultane ous ". ▁ ▁Nature ▁morte ▁shows ▁Met z inger ' s ▁particular ▁interest ▁in ▁the ▁use ▁of ▁mathematics ▁and ▁geometry . ▁In ▁Du ▁" C ub isme ", ▁written ▁the ▁following ▁year , ▁Met z inger ▁and ▁G le izes ▁proc laimed : ▁ ▁" To ▁establish ▁p ict orial ▁space , ▁we ▁must ▁have ▁rec ourse ▁to ▁tact ile ▁and ▁motor ▁sens ations , ▁indeed ▁to ▁all ▁our ▁fac ult ies . ▁It ▁is ▁our ▁whole ▁person ality ▁which , ▁contract ing ▁or ▁expand ing , ▁transform s ▁the ▁plane ▁of ▁the ▁picture . ▁As ▁it ▁react s , ▁this ▁plane ▁reflect s ▁the ▁person ality ▁back ▁upon ▁the ▁understanding ▁of ▁the ▁spect ator , ▁and ▁thus ▁p ict orial ▁space ▁is ▁defined : ▁a ▁sensitive ▁passage ▁between ▁two ▁subject ive ▁spaces . ▁The ▁forms ▁which ▁are ▁situated ▁within ▁this ▁space ▁spring ▁from ▁a ▁dynam ism ▁which ▁we ▁profess ▁to ▁domin ate . ▁In ▁order ▁that ▁our ▁intelligence ▁may ▁possess ▁it , ▁let ▁us ▁first ▁exercise ▁our ▁sens itivity . ▁There ▁are ▁only ▁nu ances . ▁Form ▁appears ▁end owed ▁with ▁properties ▁identical ▁to ▁those ▁of ▁color . ▁It ▁is ▁temper ed ▁or ▁augment ed ▁by ▁contact ▁with ▁another ▁form , ▁it ▁is ▁destroyed ▁or ▁it ▁flowers , ▁it ▁is ▁multip lied ▁or ▁it ▁disapp ears ". < ref > Jean ▁Met z inger , ▁Albert ▁G le izes , ▁Du ▁" C ub isme