“One morning I woke up, and I knew you were really gone.” That’s the first line of Déjà Vu. It’s a painful image, pulling from a rich blues tradition of narrators whose lives crash down when they wake up. If you didn’t know any better, you might imagine this line sung plaintively, slowly, over mournful chords.

That’s not what Stephen Stills has in mind at all. From the first instant of “Carry On”, bright major-key acoustic guitars charge forward, and then three perfectly braided voices hit like a blast of sunshine. The lyrics, too, turn immediately away from the dolor of the first line: “A new day, a new way, and new eyes to see the dawn.”

Déjà Vu was recorded in the last half of 1969, that brief euphoric moment between Woodstock and Altamont, when it started to seem like the movement of a generation really might change the world. That sparkling optimism turns the devastation of a lover’s abandonment into an unexpected hallelujah: “Rejoice, rejoice, we have no choice but to carry on.”

Album cover from Deja Vu

The sunny spirit carries through both of Graham Nash’s contributions to the album, “Teach Your Children” and “Our House”. The former has to be one of the most hopeful songs ever written about the generation gap, laying out a vision in which children and parents thrive through mutual respect and unshakable love. It’s not just a beautiful song, it’s a beautiful idea, expressed with much the same forward-looking spirit as “Carry On” — “the past is just a goodbye.” This is obviously a far cry from how many families operate — then and now — but Nash seems to be saying, “This is how it could be. Don’t you want that?”

“Our House” is less bold but just as sweet, limning a gentle domestic moment in another house full of love. Nash’s dulcet voice always takes the high parts when CSN sing in harmony, and his lead vocal here embodies warmth and comfort. Listening to the song, it’s almost impossible not to feel uplifted, unless you’re the sort of person who gets enraged by other people’s bliss. The scene was apparently inspired by his real domestic situation at the time, living with Joni Mitchell and her two cats, a perfect crystalline moment of happiness at home.

We also have Mitchell to thank for the album’s biggest hit, “Woodstock.” But where her original was quiet and contemplative, Neil Young and his guitar turn this version into a jagged, soaring powerhouse. It’s probably the peak of the album’s optimism too, what with the bomber death planes turning into butterflies and all. CSNY make an excellent choice to integrate the “billion year old carbon” and “caught in the devil’s bargain” lines better into the whole song — where in Mitchell’s version they almost seem like throwaways, here they anchor the chorus every time, along with the magic harmonies swirling into the sky. But it’s Young’s guitar, skittering over Taylor & Reeves’ funky rhythm section, and Stills’ emotional vocal, that makes this cover feel so vital and unforgettable.

But for all the joy that suffuses this album, there’s a dark undertow too. Where “Carry On” and “Woodstock” give us a Stills bouncing with hope for the future, “4 + 20” tells a different story altogether — he’s so heartbroken that he wishes he was dead. That’s not somebody who feels he has no choice but to carry on. Like Adele at 25, he’s a very young person who feels very old in this song.

Young delivers a better version of this ache in his lovely standout track “Helpless.” Where Stills’ account of depression delivers a straightforward narrative of loneliness, Young combines a sweet nostalgia for the past with a deeply stricken portrait of how he feels today. Where CSN’s vocal blend often feels uplifting, in this song it amplifies the sad lyric’s poignancy into an almost sobbing despair.

But still, these two songs aside, this is an album with hope for the future, or even the past. Crosby’s title track invokes the notion of past lives as a kind of key to the present, and hopes that what he learns this time around will guide him on what to do next time. (Little did he know back then just how much he’d have to learn this time around.) “Almost Cut My Hair” casts him as a soldier in the resistance, his tresses a “freak flag” for others to rally ’round.

And finally, there’s “Everybody I Love You.” As in the beginning, those gorgeous perfect harmonies reach out to embrace the whole world, the whole future. Once the song transitions from its funky beginning to its final choir of angels, the awesome stop-start technique that works so powerfully in “Woodstock” comes back to carry us into counterculture heaven. CSNY wouldn’t always love everybody, nor in fact even each other, but for that moment I believe them, and boy does it feel good.

Postscript: Listening to this album on repeat made me revisit a couple of other favorites, and I felt so connected to them that they feel like they belong here. First, Weird Al’s absolutely note-perfect CSNY parody, which is also a perfect satire of corporate buzzwords:

And finally k.d. lang’s absolutely heartrending version of “Helpless”, used to devastating effect at the end of the movie Away From Her: