▁again ▁and ▁again ▁rails ▁on ▁sing ers ▁who ▁accident ally ▁sing ▁out ▁of ▁tempo ▁or ▁self - ag grand izing ly ▁hold ▁out ▁notes ▁as ▁in ▁the ▁modern ▁ferm ata , ▁he ▁encourag es ▁“ [ t ] he ▁ste aling ▁of ▁Time ▁[ … ], ▁provided ▁he ▁makes ▁a ▁Rest itution ▁with ▁In gen u ity ” ; ▁meaning , ▁provided ▁the ▁singer ▁catch es ▁back ▁up ▁the ▁accompan iment , ▁allowing ▁them ▁to ▁keep ▁tempo . ▁ ▁Another ▁interesting ▁element ▁of ▁Op in ioni ▁is ▁T osi ' s ▁discuss ions ▁on ▁in ton ation ▁and ▁sol - fa - ing . ▁ ▁During ▁a ▁period ▁in ▁which ▁various ▁methods ▁of ▁temper ament ▁were ▁used ▁by ▁key boards , ▁strings ▁and ▁even ▁sing ers , ▁T osi ▁l aments ▁that ▁“ except ▁in ▁some ▁few ▁Prof ess ors , ▁that ▁modern ▁In ton ation ▁is ▁very ▁bad .” ▁▁ ▁He ▁speak s ▁of ▁a ▁differ ing ▁“ S emit one ▁Major ▁and ▁Minor ” ▁( or ▁a ▁larger ▁and ▁a ▁smaller ▁sem it one ) ▁whose ▁“ [ d ] ifference ▁cannot ▁be ▁known ▁by ▁an ▁Organ ▁or ▁Har ps ich ord , ▁if ▁the ▁Ke ys ▁of ▁the ▁Inst rument ▁are ▁not ▁split .” ▁▁ ▁Con sequ entially , ▁he ▁war ns ▁that ▁“ if ▁a ▁S op rano ▁was ▁to ▁sing ▁D ▁sharp , ▁like ▁E ▁flat , ▁a ▁nice ▁Ear ▁will ▁find ▁he ▁is ▁out ▁of ▁T une , ▁because ▁this ▁last ▁r ises .” ▁▁ ▁T osi