Renata Tebaldi was one of the dominant lyrico-spinto sopranos of the 1950s and 1960s, with a large, powerful voice that, despite a severely flawed top, was described by many of her admirers as one of the most beautiful of the 20th century. In many ways she and Maria Callas were defined by one another, although often far too simplistically, assuming that what one had, the other did not. (Rather like the cats versus dogs debates among pet lovers, in which all dogs are loving but dumb and all cats are bright but treacherous.) Those who backed Callas against Tebaldi denounced Tebaldi as a stodgy singer of the "this is about showing off my voice" school and lauded Callas as the genuine operatic artist who let the voice be subservient to the opera and to the drama; those who held Tebaldi to be the prima donna denounced Callas as overly erratic, with an unattractive voice that was on the edge of disaster. In fact, Tebaldi was not without a sense of the stage and of dramatic presentation, and for much of her career, in many ways Callas had the more reliable and versatile technique.