Schwarzkopf, a Marlene Dietrich look-alike with an equally glamorous voice, takes the top line in all the pieces. Seefried, whose voice and aspect both convey more a sense of Mitteleuropean stolidity than Schwarzkopf's soaring emotional extravagance, sings the harmony throughout with a remarkably affecting purity, almost an aesthetic of austerity. To me, the highlight of the album is the Dvořák duet cycle Klänge aus Mähren -- Strains from Moravia -- sung in German. In this repertoire, the two voices just seem to work together so naturally, and convey such warmth and intimacy, and such a lovely sense of the conversational, that I've always imagined that Schwarzkopf and Seefried were true friends in real life. Schwarzkopf, often expressive to the point of exaggeration, is beautifully restrained here, and the two sopranos sing together with an enviable simplicity, more touching by far than a more conventionally expressive interpretation. I couldn't find any selections of this repertoire on Youtube, so here is one of the Dvořák duets, "Fliege, Vöglein," sung by the American soprano Barbara Bonney and the German mezzo Angelika Kirchschlager.
It is lovely, but to me, it lacks something of the naturalness, the simplicity, of the Schwarzkopf-Seefried performance.
In looking for recordings of the pair on Youtube, though, I found something that I thought astonishingly beautiful: Seefried, again with Gerald Moore at the piano, singing the well-known late Mozart song "Abendempfindung" (Emotions at evening).
At first I thought the tempo was too fast, but after several bars it seemed to me the perfect framework for the delicacy and restraint of Seefried's interpretation. The text:
It is evening; the sun has vanished,
And the moon shines with its silver rays.