One of the greatest voices of the 20th century, the Swedish soprano Birgit Nilsson was born 100 years ago today. In addition to her incomparable voice, Ms. Nilsson possessed a wicked sense of humor —there are so many humorous anecdotes about her. When asked which was her favorite role, she said, “Isolde made me famous. Turandot made me rich.” When she was preparing her taxes and was asked if she had any dependents, she replied, “Only one. Rudolf Bing.” What was her answer when she was asked the secret to singing the role of Isolde?