There were singer-songwriters before Joni Mitchell, but with her 1971 masterpiece Blue, she pretty much set the template for almost everything that came after it.

Leading up to the album's release on June 22, Mitchell had released three albums, each an improvement -- commercially and creatively -- over its predecessor. Her 1968 debut, Song to a Seagull, barely cracked Billboard's Top 200 album chart and was short on any signature song. But by the following year's Clouds, she was in the Top 40 and writing and recording numbers like "Chelsea Morning" and "Both Sides Now," two of her earliest classics.

With 1970's Ladies of the Canyon she cracked the Top 30 for the first time and scored three more of her most enduring numbers, "The Circle Game," "Woodstock" (which Mitchell's ex, Graham Nash, took to the Top 15 with his group Crosby, Stills, Nash & Young) and "Big Yellow Taxi," which gave Mitchell her first sorta big single - it stalled at No. 67, but its influence over the years looms way larger.

But Blue was something different, a hyper-personal collection of songs that sounded like they were ripped straight from Mitchell's diary. The spare performances -- most times it's just Mitchell and her guitar or piano -- add to the album's intimacy, sparking a revealing listen that at times comes off like something maybe you shouldn't be hearing. There are confessions, slipped-out secrets and the sense that the heart on display here was temporarily caught off guard.

When she first started recording the album in Los Angeles (with famous friend Stephen Stills and current boyfriend James Taylor helping out on a handful of songs, along with pedal steel player Sneaky Pete Kleinow and drummer Russ Kunkel), Mitchell was unsure which direction her fourth album was heading. Songs were recorded and later cut from the album, replaced by newer numbers that better reflected her state of mind at the time. Blue is as much about her breakup with Nash as it is her relationship with other men of the period, including Taylor, even though the couple was history by the time the album came out. The pieces come together like a fractured heart trying to mend itself.

Mitchell didn't try to hide any of this. The hurt you hear in some of the songs came from a very real place, as did the joy found in others. In songs like "Carey," "California," "River," "A Case of You" and the title track, Mitchell paints a portrait of a life in shambles, in heartbreak, in excitement and in love. (Many of the joyous pieces were written about a man Mitchell met during a quick retreat to Greece in 1970 after her breakup with Nash.)

But there was more to Blue than just veiled accounts of Mitchell's flings. There were songs about the daughter she gave up for adoption in 1965 ("Little Green"), homesickness ("California") and her early marriage ("The Last Time I Saw Richard"). Nobody ever opened up so much on record before. Not Carole King, whose equally game-shifting singer-songwriter album Tapestry was released just four months earlier, and certainly not any of her male contemporaries.

Blue became Mitchell's highest-charting album at the time, making it all the way to No. 15 (in her native Canada, she cracked the Top 10 for the first time). "Carey" and "California" were both released as singles, with only the former charting, making it to No. 93. But its influence was almost immediately felt. Her friends and peers celebrated her openness, her complex guitar tunings and her willingness to take music into a bold new direction.

With the charts dominated by macho braggarts like the Rolling Stones' Sticky Fingers and Rod Stewart's Every Picture Tells a Story, both of which sandwiched Tapestry in the No. 1 spot in 1971, Blue not only revealed rare vulnerability, it was willing to take responsibility for its creator's f----ups. Nobody else was doing that. All these years later, singer-songwriters of all sorts (sensitive, insensitive, confessional, regretful) can be traced back to Mitchell's masterpiece. A new era begins here.

See Joni Mitchell in 1971's Best Rock Albums