ferrari's 'presque rein' (1967-1970) is regarded as a classic of its kind. in it, ferrari takes a day-long recording of environmental sounds at a yugoslavian beach and, through editing, makes a piece that lasts just twenty-one minutes. it has been seen as an affirmation of john cage's idea that music is always going on all around us, and if only we were to stop to listen to it, we would realise this. ferrari continued to write purely instrumental music as well as his tape pieces. he also made a number of documentary films on contemporary composers in rehearsal, including olivier messiaen and karlheinz stockhausen.