I'm glad people who didn't know who are discovering it's a cover, not just because Trent Reznor deserves that much, but because I think the fact that Cash did not write it is crucial to the power of his version. This is a young man's song about suffering, about addiction and self-destruction in youth. And Cash is, in the most majestic possible way, taking that and going "oh kid, you have no idea", and changes the meaning without changing the lyrics (except for a single word). In his voice, on his face, in his aged hands on the guitar and piano, it becomes about the agonising brevity of life, the irretrievability of mistakes, and the inevitable loss of everything, including a recognisable self. But the creativity of repurposing only shows if you can still see what was originally there.