Cash himself, in his 1997 book "" commented, "I was there - I was the first to arrive and the last to leave, contrary to what has been written - but I was just there to watch Carl record, which he did until mid-afternoon, when Elvis came in with his girlfriend. At that point the session stopped and we all started laughing and cutting up together. Then Elvis sat down at the piano, and we started singing gospel songs we all knew, then some Bill Monroe songs. Elvis wanted to hear songs Bill had written besides "Blue Moon of Kentucky", and I knew the whole repertoire. So, again contrary to what some people have written, my voice is on the tape. It's not obvious, because I was farthest away from the mic and I was singing a lot higher than I usually did in order to stay in key with Elvis, but I guarantee you, I'm there."