The "Neruda Songs" by the late Peter Lieberson, which the Minnesota Orchestra is performing this week, have been acclaimed the most important — and arguably the most sensuously beautiful — works for solo voice and orchestra to be composed in this century.

The songs are settings of five sonnets by Chilean poet Pablo Neruda that deal, in the composer's words, with "different faces of love," the final one being the inevitability of parting through death.

Lieberson composed the songs in 2005 for his wife, the much-admired mezzo-soprano Lorraine Hunt Lieberson. The intent was for her to sing them, which she did, in high-profile performances in Los Angeles and Boston, and then record them.

The extra resonance to this was that Hunt Lieberson was battling breast cancer at the time of the premiere, and just a year later the illness took her life at age 52. A line from one of the poems seemed prophetic: "My love, if I die and you don't, let's not give grief an even greater field." Five years later, Lieberson died from complications of lymphoma.

It was possible that these songs, having been hatched with a particular voice in mind — a distinctive one in the case of Hunt Lieberson — might not be taken up by other singers. However, Robert Spano, music director of the Atlanta Symphony and a champion of new music, put together his own recording of the Neruda songs, using that orchestra and a rising young American mezzo, Kelley O'Connor, who studied the songs with Lieberson while he was undergoing chemotherapy in Hawaii.

Happily, Spano and O'Connor have been engaged for the concerts at Orchestra Hall. Thursday morning's performance was one of almost startling illumination and poignancy. O'Connor seemed to have thought through every nuance and shade of meaning in these evocative texts and the settings that Lieberson created for them, and yet the performance sustained a feeling of spontaneity and an intimacy not easily achieved in this hall. (Wisely, translations of the poems appeared as surtitles above the stage as the performance progressed.)

Hunt Lieberson's recording on Nonesuch (taped live in Boston) will always be cherished, but there was a freshness and flexibility to O'Connor's singing — the strong, clear high notes, for instance, in the first song — that the older singer couldn't quite realize. O'Connor also captured the urgency in the third song ("Will you come back? Will you leave me here, dying?"), and the tone of the final song, the one that most recalls Richard Strauss, ending in a state of tranquility with a repetition of the word "amor," was positively radiant.

Spano displayed an easy command of the score's varied and complicated textures — the "sultry" and "languid" qualities the composer asks for — and its subtle rhythms. (Some percussion effects in the bossa-nova movement, the fourth, were a little too soft.)

The second half was devoted to Tchaikovsky's familiar Symphony No. 6, "Pathetique." Spano's reading was amply emotional without turning sentimental, and he drew a fine performance from the orchestra: a big, growling sound from the trombones and admirable momentum in the third movement.

Michael Anthony is a Minneapolis music writer.