▁grammar , ▁diction , ▁social ▁decor um ▁and ▁acting . ▁ ▁All ▁the ▁standard ▁orn aments ▁of ▁the ▁time ▁are ▁thoroughly ▁presented : ▁app og gi atura , ▁mess a ▁di ▁voce , ▁eight ▁kinds ▁of ▁tr ills , ▁pass aggi ▁( div isions ), ▁and ▁port amento . ▁ ▁T osi ▁also ▁dedic ates ▁a ▁chapter ▁each ▁to ▁rec itative ▁and ▁aria ▁singing , ▁pre aching ▁throughout ▁the ▁necessity ▁of ▁impro vis ing ▁one ' s ▁own ▁gra ces ▁and ▁divisions ▁on ▁the ▁spot ▁in ▁performances . ▁ ▁There ▁are ▁a ▁few ▁teach ings ▁of ▁T osi ' s ▁in ▁his ▁Op in ioni ▁that ▁have ▁been ▁particularly ▁interesting ▁to ▁sing ers ▁and ▁sch ol ars ▁over ▁the ▁years . ▁ ▁T osi ▁clearly ▁advoc ates ▁unit ing ▁and ▁bl ending ▁the ▁ch est ▁and ▁head ▁registers , ▁ ▁the ▁first ▁recorded ▁vocal ▁ped agog ue ▁to ▁do ▁so . ▁ ▁While ▁earlier ▁writers ▁such ▁as ▁Z ac con i ▁ ▁and ▁C acc ini ▁stated ▁that ▁sing ers ▁ought ▁to ▁only ▁sing ▁in ▁their ▁“ natural ▁voice ,” ▁T osi ▁went ▁so ▁far ▁as ▁to ▁say ▁“ [ I ] f ▁[ the ▁ch est ▁and ▁head ▁register ] ▁do ▁not ▁perfectly ▁un ite , ▁the ▁Vo ice ▁will ▁be ▁of ▁divers ▁Register s , ▁and ▁must ▁consequ ently ▁lose ▁its ▁Beaut y .” ▁▁ ▁T osi ' s ▁is ▁also ▁the ▁first ▁recorded ▁encourag ement ▁of ▁the ▁use ▁of ▁rub ato ▁as ▁an ▁emb ell ishment . ▁ ▁While ▁he