This combination of size, weight, range and agility was a source of amazement to Callas's own contemporaries. One of the choristers present at her La Scala debut in "I vespri siciliani" recalled, "My God! She came on stage sounding like our deepest contralto, Cloe Elmo. And before the evening was over, she took a high E-flat. And it was twice as strong as Toti Dal Monte's!" In the same vein, mezzo-soprano Giulietta Simionato said: "The first time we sang together was in Mexico in 1950, where she sang the top E-flat in the second-act finale of "Aida". I can still remember the effect of that note in the opera house—it was like a star!" For Italian soprano Renata Tebaldi, "the most fantastic thing was the possibility for her to sing the soprano coloratura with this voice! This was something really special. absolutely!"