There seems little point in repeating the praise heaped on these landmark recordings already in so many excellent reviews. When I first heard "Raising Sand" in 2007 it was obviously destined not for musical obscurity but for some kind of greatness, and since then I've listened to these songs hundreds of times in the morning, the evening, on lazy summer afternoons and driving through the mountains of Andalusia in an open-topped sports car. It's one of those rare occasions when dedicated professionalism, inspired musicians with a love for the material and first-rate production know-how come together to create something remarkable and hard to categorise.
Robert Plant has always had a deep interest in, and understanding of, the many strands of traditional American folk music. Anyone familiar with his back catalogue over the past 40 years will see evidence of this interest and of his ability to interpret traditional styles like slow blues, R&B and folk-country in new ways. Just listen to "Babe I'm gonna leave you" from Led Zeppelin's first album in 1969 - it goes back that far.
Alison Krauss has spent a career playing bluegrass - she's a great fiddle player too - and in Plant has found what seems to be her perfect musical match. This superficially improbable collaboration has given birth to something truly wonderful. Plant's voice turns out to be perfect for bluegrass and brings a depth of feeling - yet with a light touch - to complement Krauss's serene and beautiful singing in harmonies of such richness and serenity they raise the bar in the same way Simon & Garfunkel did way back in the 1970s (though the analogy is confined to the quality of the harmonies and goes no further). The care and respect they have for the material is obvious in the quality of the resultant product. The album cover carries a MOJO quote: "The musical relationship between Krauss and Plant is so gentle, attentive and respectfully intimate it feels more like a courtship dance" - perfect summary.
It's a great, great album, and something of a benchmark. If you've never heard it, you should. You'll likely listen to it for years and years, and love it more every time - like the rest of us.