Like a lot of classics of British blues, Fleetwood Mac’s 1968 debut alum is a balance between progress and tradition. As Mick Fleetwood later wrote, the band members didn’t have the same cultural claim to the blues that American musicians might have. But they were also coming out of a World War that decimated their country’s infrastructure, to a degree America hadn’t experienced. Not to mention the fact that by the time Fleetwood and his peers were picking up the music, the country it came from had all but left it behind. Compared to similar efforts by Cream, or even The Rolling Stones, the music on Peter Green’s Fleetwood Mac is conservative: They don’t try to modernise the blues with psychedelia, or mainstream it with pop. But it also never sounds like a museum piece. The atmosphere is humid, a little druggy, a little noisy. The covers (including Robert Johnson’s “Hellhound on My Trail” and Elmore James’ “Shake Your Moneymaker”) might help you hear old styles with new ears. And the originals—especially Jeremy Spencer’s “My Heart Beat Like a Hammer” and the Latin-influenced “I Loved Another Woman”—tell you more about the 1970s than the 1950s (you can hear their long hair even if you can’t see it). Most listeners will probably come to Fleetwood Mac’s first album because of the band they became. Here’s where they started.