In 1974, Stevie Wonder was the most critically revered pop star in the world; he was also considering leaving the music industry altogether. So when Songs in the Key of Life was released two years later, demand was so high that it became, at the time, the fastest-selling album in history. All was forgiven. Wonder positioned himself as the benevolent overlord of a vast self-drawn cosmos, one with a remarkable cache of songs: Songs in the Key of Life, which runs nearly 90 minutes, is effortlessly melodic, broad in scope, deeply personal—and often just plain weird. In the era of the overblown rock epic, Wonder had created the most searching and sprawling soul album ever released. Start with the brassy, hook-filled and positively effusive chart-topping singles “Sir Duke” and “I Wish”, both of which have soundtracked countless barbecues and wedding receptions for decades. At the other end of the spectrum: the stark reality-soul of “Village Ghetto Land” and “Pastime Paradise”, on which Wonder leaves the bandstand for the op-ed pages to decry the abandonment of the civil rights dream. Then Wonder’s daughter Aisha shows up in the sugary Girl Dad anthem “Isn’t She Lovely”. As Songs in the Key of Life nears its conclusion, Wonder clears the dance floor for 15 minutes of sumptuous gospel-disco in “As” and “Another Star”. But the album’s defining moment might come on a bonus track, one originally issued as an extra 45 with the album’s vinyl release. It starts in deep space with the Afrofuturist fantasia “Saturn”, but as its last synthesiser chords fade out, Wonder zooms light-years to an urban playground where we can hear the sound of Black children skipping Double Dutch. Sonically, culturally and emotionally, Songs in the Key of Life is much more than a gigantic collection of songs—it forms an entire world view.