Wagnerians often complain that in the 1930s and ’40s, opera goers could thrill to voices such as the Norwegian soprano Kirsten Flagstad and the Danish tenor Lauritz Melchior, the likes of which have vanished from the earth. While this is doubtless true, some exceptional singers bridge the gap between the Golden Age and today by being able to sing operasthatrequireheroicvocalstamina. The Swedish soprano Birgit Nilsson (1918–2005),who said that the key requirement for singing Wagner’s Isolde was a “comfortable pair of shoes,” was one such, with a career thriving from the late 1950s to around 1980.

At first listen, Nilsson’s voice seems to resemble a wind machine operated with lasers, with high notes of improbable size and intensity shrieked out with clockwork regularity. Yet her voice at its best also radiates fierce integrity and gritty commitment, an absolute involvement in the ongoing drama which is ideal for any singing actress.

Now a welcome new translation of the diva’s memoirs, “La Nilsson: My Life in Opera” (Northeastern University Press, 308 pages, $35), has appeared. Originally published in her native Sweden in 1995, the book was translated into German in 1997, and it was from this version that the English edition has been prepared by Doris Jung Popper. It might seem surprising for a university press to offer the translation of a translation, but the translator, born in Centralia, Ill. in 1924, is herself a retired Wagnerian soprano. She sang onstage in Germany alongside major Wagnerians such as Astrid Varnay and Wolfgang Windgassen, gaining the reputation of a solid, reliable singer. Would that all translators had such pertinent career experience related to the books they tackle!

As for the subject of “La Nilsson,” she was born on a farm some 60 miles north of Malmö, Sweden, and enjoyed repeating her mother’s advice: “Stay close to the earth. Then when you fall down, it won’t hurt so much.” This farm girl had no time for affectation or pretense, and Nilsson offers a new viewpoint of the long overrated Decca recording of the Wagner “Ring,” doubtless a landmark in recording history, but not, Nilsson suggests, in musical history. She scorns the conductor Georg Solti’s penchant for “almost unbearable loudness” in orchestral playing, while she finds Decca recording producer John Culshaw far less useful than EMI’s producer Walter Legge.

Nilsson unequivocally contradicts the “lies” published by Culshaw in a memoir according to which her friend and compatriot, the tenor Jussi Björling, was fired from a Solti recording shortly before his death because — according to Culshaw — he was “drunk and not musically prepared.” Nilsson asserts with the doughty fidelity of one of the heroines whom she incarnated onstage that Björling was not drunk, and was fired after he complained about the heat in the recording studio and challenged Solti’s musical preparation.

This kind of redoubtable truth-telling, oblivious to the vanities of stars of the music world, alternates with a fair amount of earthy detail, such as the disclosure that a young Birgitte paused on her way to an audition at Sweden’s Royal Academy of Music in order to relieve herself through the slats of a park bench. Or the information that in Argentina’s Teatro Colon in the 1950s, when singers walked “from the dressing rooms past the men’s restroom, the smell was so awful that it brought tears to one’s eyes.”

This same kind of dauntlessness is communicated in Nilsson’s best recordings, such as a 1956 live “Fidelio” conducted by Erich Kleiber on Koch Schwann and 1970s studio versions of Richard Strauss’s “Die Frau ohne Schatten” (Woman Without a Shadow) and Weber’s “Oberon,” both on Deutsche Grammophon. Among Nilsson’s many recordings of the role of Isolde in Wagner’s opera, one of the best is the earliest, from a 1957 Florence production conducted by Artur Rodzinski on the Living Stage label.

Nilsson recorded many Italian roles in operas by Verdi and Puccini, but some may feel that the one closest to her own personality was the bold cowgirl Minnie in Puccini’s “La fanciulla del West” (Girl of the Golden West) in a 1958 EMI recording. A better dramatic musician than even her admirers may admit, Nilsson bloomed in recordings with conductors as varied as Rafael Kubelík, Otto Klemperer, Hans Knappertsbusch, and Rudolf Kempe. “La Nilsson” reminds us of a splendid singer’s variety and humanity, and for this we should feel grateful.

Mr. Ivry last wrote for these pages on Edith Piaf.