According to the book “Opera” published by Koenemann, Cossotto was one of the leading Italian mezzo-sopranos of the ’60s and ’70s. She has performed with the likes of Maria Callas (one of the most renowned and influential opera singers of the 20th century). The relationship with Maria Callas was tainted when Callas walked out just after their duet, Mira, o Norma. Some claimed that Cossotto intentionally sabotaged Callas by singing over Callas and holding high notes longer than what was considered in good form. Even though Callas died in 1977, the controversy and debate lives on.
