McCartney may have made more people happy—gapingly, tinglingly, mind-cancelingly happy—than any other artist, alive or dead. W. H. Auden wrote, In headaches and in worry / Vaguely life leaks away. Paul McCartney has been the opposite of that. The rush of early Beatles; the towering artistic magnanimity of middle-period Beatles; the epic fragmentations of late Beatles; and his solo songbook, which sometimes feels like a wild succession of one-hit wonders, of brilliant, bulbous, unrelated novelties—in every phase, in every style, he has insisted that we not allow our lives to leak away. His scope is immense. Think for a second about Revolver, and try to hold in your head the idea that the Larkin-esque elegist who wrote “Eleanor Rigby”—that rhapsody of glumness, that death-of-God song—is also the man playing bass on “And Your Bird Can Sing,” with a technique as restless and fiery-fingered as The Who’s John Entwistle’s but with an extra dimension of melodic bounteousness and buoyancy, of pure, generative tune-energy. (I just listened to it again, and burst out laughing.)

“Penny Lane” is the perfect summation, in a way: a trippily colorized vision of everyday life as a harmonic whole, a sublime congruity or comedy, a humming, sanctified circuit in which the brass-band trumpeter sounds like Bach and the fireman keeps a portrait of the Queen in his pocket. If you watched McCartney recently on James Corden’s “Carpool Karaoke,” doing a nostalgia tour of Liverpool with his host blushing and chirping at the wheel, you’ll have seen how people—young, old, of every shape and color—respond to him. He travels in a pocket universe of delight. You’ll also have seen him carefully adding his signature to the scuffed, graffitied street sign of the real Penny Lane: signing it like an artist signs his creation.

“Poetry reveals language’s underlying metrical and intonational regularity, and its tendency to pattern its sounds,” the Scottish poet and musician Don Paterson writes in his new book, The Poem. Poetry does that, and so does Paul McCartney. He can’t help himself. Swaying daisies sing a lazy song beneath the sun. That’s from 1968’s “Mother Nature’s Son,” perhaps the single most pristine utterance of McCartney’s muse in his whole corpus. The softly dulled guitar-chime, the foot-tap and the lulling rhyme, the sleepy delivery: Find me in my field of grass / Mother Nature’s son. This is not 20th-century music. It has nothing to do with sex, politics, the trapped self, or the long chore of consciousness. This is pre-modern, pre-adult, pre-gravity. It runs straight back to the first climates of the imagination, to the place where William Blake wrote his Songs of Innocence: Piping down the valleys wild / Piping songs of pleasant glee / On a cloud I saw a child.

And then, from the same era and acoustic realm, there’s “Blackbird,” shimmering in the predawn: Take these broken wings and learn to fly. For me this is McCartney self-soothing in the face of the Beatles’ meltdown, the impending bummer of individuation. It was from the White Album sessions, after all—everybody writing his own songs, grumpy, with Yoko Ono sitting harbingerlike in the studio, a carved, impassive face in a cavern of hair. So what’s a sad but incorrigibly optimistic bandleader to do, if not direct himself right into the dark, into the lustrousness, into the deep blackbird-feather gleam of promise? Blackbird, fly / Blackbird, fly / Into the light of the dark black night. (Limpid squirtings of actual blackbird-song conclude the track, the bird as compulsive a melodist as McCartney himself.)