 Berio described the main structure of Laborintus II as a " catalogue , in its medieval meaning " ( exemplified by the <unk> of <unk> of Seville ) , using Dante 's themes of " memory , death and usury " . Members of the Dutch choir Nederlands Kamerkoor , which performed in the recording , have also cited usury as a key theme in the work , describing the composition as " an <unk> against the practice " . Of the form , Berio wrote : " Individual words and sentences are sometimes to be regarded as autonomous entities , and sometimes to be perceived as part of the sound structure as a whole . " The instrumentation of Laborintus II was written as an " extension " of the vocal material ; its electronic section is likewise an extension of the instrumental music . Berio used car tyres and a blow @-@ up doll on stage in a performance of the work at the Holland Festival in 1973 . 
