The roots of this Peter Green-penned song date back to Green's "I Loved Another Woman" from the band's 1968 self-titled album, which has a similar song structure and melody, but a few months later Green fleshed it out, added in a hint of psychedelia and a slight Latin twist, and turned it from a traditional blues vamp into a timeless classic. It was released as a single and appeared on some comps the next year, but a lot of people first heard this song when Latin psychedelic rockers Santana turned it into a hit with their 1970 cover, which Peter green approved of, as evidenced when he performed the song with Santana at The Rock and Roll Hall of Fame. Santana breathes new life into the song, but the original still stands tall. It proved how quickly Green was progressing as a songwriter from the traditional blues he had been writing just months earlier, and it remains a gem of the original psychedelic rock era.

Fleetwood Mac's first chart-topping hit was, surprisingly, an instrumental. Peter Green didn't want Fleetwood Mac to be pigeonholed as a blues band, and only months after "Black Magic Woman," Green took their sound in a drastically more exploratory direction on this psychedelic, meditative single. It was the band's first recording with new guitarist Danny Kirwan, whose vibrato-ing style provided a nice complement to Green's fiery playing, and their guitars intertwine beautifully on this song. It is said to have directly inspired The Beatles' "Sun King" from Abbey Road and to have greatly inspired David Gilmour's guitar playing in Pink Floyd, and the influence didn't stop there. Comparatively modern guitar heroes Lee Ranaldo (Sonic Youth) and J Mascis (Dinosaur Jr) covered it together for the 2012 tribute album Just Tell Me That You Want Me, and it's not hard to see why those two musicians would pick this one.

As Peter Green continued to push past the barriers of blues rock (and continued to take more LSD), he began developing a knack for melancholic, psychedelic folk that he first perfected on the 1969 single "Man of the World." It's hard not to draw parallels between Peter Green and Pink Floyd's Syd Barrett (another reclusive psychedelic mastermind behind a late '60s UK rock band that got much more famous in the '70s without him), and those parallels are even more obvious on introspective songs like "Man of the World." Peter sings somberly about loneliness and depression and the instrumental backdrop is about as hushed and bare-bones as Fleetwood Mac got at that point. It's a heartbreaking masterpiece.

Peter Green's growing interest in psychedelia and folk music and the increased singing and songwriting input from Danny Kirwan -- whose contributions were praised and encouraged by Peter -- led to Fleetwood Mac's third full-length and first timeless album, Then Play On. It's a masterpiece that blends blues, rock, psychedelia, folk, flamenco, classical, and more (and has stunning artwork), and it's as essential as anything Fleetwood Mac released in the Buckingham/Nicks era but for entirely different reasons. "Coming Your Way," the Kirwan composition that opens the album, sets the tone for it perfectly. The song uses blues rock as a starting point, but it goes in all kinds of other directions from there. Kirwan and Green's guitars are in constant conversation with each other, Mick Fleetwood's polyrhythmic percussion livens things up and never relies on a traditional blues beat, and the song eventually evolves into a doomy coda that qualifies as proto-metal. It's a leap from anything Fleetwood Mac had released before it, and once hard rock and progressive rock became popular in the 1970s, this song would prove to be ahead of its time.

Going further in the direction of "Man of the World," Peter Green contributed this lonely, sorrowful, psychedelic folk song to Then Play On. He's frequently celebrated as a guitarist, but it's songs like this that really show how innovative of a songwriter he was, and how much untapped potential he had in this realm. His debut solo album, 1970's The End of the Game, is a jammy, psychedelic, instrumental album, but had he instead chosen to release a singer/songwriter album, we'd be talking about Peter Green the way we talk about Nick Drake and Vashti Bunyan. This song proves it.

Peter Green wasn't the only Fleetwood Mac member developing an ahead-of-his-time psychedelic folk songwriting style on Then Play On. Danny Kirwan was emerging as a crucial contributor in that same department, as evidenced by such songs as "Although the Sun Is Shining" and "When You Say." The latter is a hauntingly beautiful song that helped introduce vocal harmonies to Fleetwood Mac, and which gained the approval of Christine Perfect -- later known as Christine McVie -- who was a Fleetwood Mac contributor at the time, soon to be an official member, and who did her own great version of this song on her debut 1970 solo album.

There are a lot of great songs on Then Play On, but its crowning achievement was a song that was initially left off the album but then added to revised versions after becoming a successful non-album single, "Oh Well." It's an eight-minute song made up of two parts, and it's Peter Green's masterpiece. Almost every side of his songwriting was represented on this song and then some: fiery blues riffs backed by Mick Fleetwwood's increasingly atypical drumming, somber folky passages, baroque pop instrumentation, flamenco-inspired guitar, and more, and it was all tied together by some of Green's most commanding singing and songwriting. It's clearly a huge inspiration on progressive rock, and it's as successfully ambitious as other 1969 triumphs like Abbey Road, Tommy, and In the Court of the Crimson King. The song unfortunately tends to overshadow much of Peter Green's other fantastic material, but that's bound to happen when a song is this close to perfect.

Fleetwood Mac hinted at a doomy direction towards the end of Then Play On opener "Coming Your Way," but they went full proto-metal on the last song Peter Green contributed to Fleetwood Mac before his departure, 1970's "The Green Manalishi (With the Two Prong Crown)." It became a popular song for Judas Priest years later and there are also well-known covers of it by Melvins and Corrosion of Conformity, and it's not hard to see why metal bands took to this one. It's as crucial to the development of heavy metal as anything Black Sabbath released that same year. It's as psychedelic and ahead-of-its-time as any of Green's best songs, but darker and heavier than all of them. Neither he nor Fleetwood Mac ever released anything quite like it ever again.

As we all know, Fleetwood Mac eventually recovered from Peter Green's departure, but it didn't happen quickly or immediately. Their first album without him, 1970's Kiln House, saw the return of early guitarist/vocalist/pianist Jeremy Spencer (who was on Fleetwood Mac's first two albums but sat out of much of Then Play On and other singles from the era), and Spencer's Kiln House contributions were often 1950s parodies that sounded regressive compared to the forward-thinking Then Play On. Danny Kirwan's contributions underwhelmed compared to the music he had written for Then Play On, but he would get his groove back on the 1971 single "Dragonfly," which sounded like the true successor to his Then Play On contributions and which Peter Green is said to have called "the best thing [Kirwan] ever wrote." It's right up there with "When You Say" and "Although the Sun Is Shining" as a hazy, hypnotic, psychedelic folk song and it's a shame that it became such an obscurity. (It's currently not on streaming services, but the upcoming Fleetwood Mac: 1969 - 1974 will finally change that.) Kirwan, perhaps the most underrated member in Fleetwood Mac history, would prove to be the bridge between the Peter Green era and the poppier '70s era, though he'd part ways with the band before their massive breakthrough (and then led a good but often-ignored solo career). Many of the best early '70s Mac compositions were his.

"Dragonfly" brings us to "Woman of 1000 Years," the Kirwan composition that opened 1971's Future Games, the first album to feature Christine McVie as an official member, first album to feature Bob Welch, and an improvement upon Kiln House in every way. With McVie, Welch, and Kirwan, Fleetwood Mac could now really start developing the harmony style that McVie, Buckingham, and Nicks would make famous, and that was heard right away on "Woman of 1000 Years." Like many of Kirwan's best songs, it's hazy psychedelic folk, with gentle acoustic guitar, barely-there production, and an ethereal atmosphere in the background. It's a progression from Then Play On but not yet in the California pop rock territory that Bob Welch would take Fleetwood Mac in. It's a gem.

"Woman of 1000 Years" is one of two genuinely brilliant songs that Danny Kirwan contributed to Future Games, the other being the 7+ minute "Sands of Time." It gets more into upbeat rock territory than "Woman of 1000 Years" and it features Kirwan and Welch facing off in its lengthy guitar-heavy mid-section, but it's still fueled by a gentle acoustic jangle, soaring harmonies, and some of Kirwan's finest songwriting.

Following one more album with Danny Kirwan (1972's Bare Trees, which featured underrated Kirwan gem "Dust" and early Bob Welch fan fave "Sentimental Lady"), Fleetwood Mac said goodbye to Kirwan and hello to guitarist Bob Weston and vocalist Dave Walker on 1973's Penguin. With Bob Welch and Christine McVie emerging as the band's new leaders, Fleetwood Mac started to perfect the pop rock style that would make them famous and the McVie-penned album opener "Remember Me" is one of the finest examples of this. It's the kind of breezy folk rock that would typify so many of Fleetwood Mac's beloved late '70s songs, and it comes with plenty of the band's soon-to-be-trademark harmonies as well as some searing lead guitar work. It's too bad this one didn't get carried over into the Buckingham/Nicks era; it would've fit right in.

Bob Welch started to solidify his position as the band's new leader on their second album of 1973, Mystery To Me, and one of his contributions was a song that would become a minor hit, remain a live staple into the Buckingham/Nicks era (and then get revisited for the first time in 41 years on the band's 2018 tour), and help set the tone for the dreamier side that Stevie Nicks would bring to the band, "Hypnotized." It has the pop appeal that many of Bob Welch's songs did, but it's hazy in a way that recalls the band's psychedelic era, and when Welch and McVie harmonize on the chorus, it's genuinely, uh, hypnotic.

As long as we're making puns, it's a "mystery to me" that Mystery To Me closer "Why" isn't a more well-known song. It's written and sung by Christine McVie and features lovely slide guitar by Bob Weston, and it's an earthy, folky, string-laden ballad that recalls the '71/'72 era of Fleetwood Mac while hinting towards the hit-making band of the later '70s. If you love later Christine McVie songs like "Over My Head" and "Songbird," you need "Why" in your life too.

Even more so than "Why" and "Remember Me," the early Christine McVie song that most foreshadowed the songs she'd write in the Buckingham/Nicks era was "Come A Little Bit Closer" from 1974's Heroes Are Hard to Find, the last album with Bob Welch before he was replaced by Lindsey Buckingham and Stevie Nicks. It's a glistening, mid-tempo piano pop song that rivals McVie's biggest songs in terms of her deft melodicism and powerful vocals. It's pure bliss.

"Come A Little Bit Closer" would've fit snugly on Fleetwood Mac's 1975 self-titled album without anyone batting an eye, but here's a Christine McVie song that's more of an oddity in her oeuvre. It has a dark, propulsive feel that's like the missing link between Then Play On and Tusk, and McVie manages to turn the brooding song into something that sounds bright and uplifting on the chorus. It's an eccentric, timeless song that would've stood out in any Fleetwood Mac era.