1971, is really remarkable. The hand splicing of all the tape loops, stringing yards and yards of tape up around the studio using mic stands, in order to get the loops right, and then when it came time to mix the thing, it took all hands on the mixing board at the same time, to do the ridiculous pans left and right, and the ups and downs.... no computers to just back it up and fix it. They were "performing" on the mixing of the dang thing. One person screwed up, start all over again. It's just recorded and engineered to perfection. Then on top of all of that, it was probably the last time they actually worked as a full team of a band, with everyone's input and ideas worked on as a team. It is really a remarkably well written, amazingly performed, and just unbelievably well mixed and engineered recording. One of the all time best.