“Wish You Were Here” opens up with a distant chord progression from Gilmour’s 12-string acoustic guitar, processed to sound as though it’s emanating from a...

“Wish You Were Here” opens up with a distant chord progression from Gilmour’s 12-string acoustic guitar, processed to sound as though it’s emanating from a car stereo. The sound crackles and pops, and when a second guitar swoops into the mix, the disparity between both parts is thrown into sharp relief. The second guitar is loud and blemish-free; the first is just a ghost, a pale shadow of what it must’ve sounded like when it was originally recorded.

By 1975, Syd Barrett had become a pale shadow of his former self, too. When he made a surprise visit to Abbey Road on June 5, stumbling into the studio while engineer Brian Humphries tweaked the final mix of “Shine On You Crazy Diamond,” he’d put on so much weight that the others didn’t recognize him for several minutes. He’d shaved his head, too, along with his eyebrows. It pained Waters to see his friend so lost, so detached, so disengaged from the world around him.“Wish You Were Here” deals with that mental inability – the refusal, even – to engage with reality, and it served as much as a rallying for Waters as a sad tribute to Barrett’s better days.