Gordon Lightfoot’s best songs have never been overly complicated things. Save for some light backing flourishes, classics such as “Sundown,” “Carefree Highway,” and “If You Could Read My Mind” are little more than his poetry and philosophical wanderings on full display. With Solo, a suite of stripped-back vocal-and-acoustic-guitar songs, there’s even less for the legendary Canadian singer-songwriter to hide behind. While it’s his first newly heard music since 2004’s Harmony, the writing actually predates that album. Lightfoot happened upon a cache of material he’d first recorded in 2001 and 2002, just prior to suffering an aortic aneurism, while cleaning his Toronto home. He took the demos and attempted to arrange them for his band, but ultimately decided to redo them with almost no additional production. The result has a particularly live-sounding immediacy and intimacy, which suits the subject matter, whether it’s the prescient “E-Motion” (which explores oversharing in the internet age), the wistful opener “Oh So Sweet,” or the reflective “Return Into Dust.” At age 81 and 21 albums in, though, Lightfoot is most revealing on the closer, “Why Not Give It a Try,” a track about keeping life fresh and challenging, and never slowing down.