Top to bottom maybe the Zep's best album, Jimmy did a masterful job on it's production, he kept it all close and tight centered around Bonzo's kit, and didn't give in to a lot of the excesses of the late 60's that were spawned by Phil Spector, Brian Wilson, Sir George Martin and some of their acolytes. The Zep were a three piece and Jimmy wanted them to sound like a great three piece should sound. Side ones' closer "Thank-you" may be the greatest vocal performance of Robert Plant's career, restrained, passionate and powerful all within the borders of this beautiful, melancholic expression of loving someone and having that love returned, much like the album.