The Mind Left Body Jam

In the early '70s the Dead would sometimes play thematic instrumentals that seemingly sprang fully-formed out of nowhere in the midst of jams and then disappeared again. Some of these, sadly, were played only once - including the "Beautiful Jam" in the 2/18/71 Dark Star -
http://www.archive.org/details/gd71-02-18.sbd.orf.107.sbeok.shnf
the "almost-China Cat jam" in the 8/14/71 Other One -
http://www.archive.org/details/gd71-08-14.sbd.ladner.21268.sbeok.shnf
the lovely, unusual cross between Bobby McGee and Bid You Goodnight that pops up at the end of the 3/22/72 Caution (available on the Rockin' the Rhein bonus disc) -
and the long, tantalizing "almost-Spanish jam" in the 7/25/72 Other One.
http://www.archive.org/details/gd72-07-25.sbd.cotsman.7046.sbeok.shnf
But other instrumentals would pop up in show after show, eventually to be named by collectors.

One of these was the Mind Left Body Jam, a simple passage of four descending chords that was named because of its similarity to the chords in 'Your Mind Has Left Your Body', a song on Paul Kantner's album Baron von Tollbooth and the Chrome Nun. Garcia was in the studio a lot with Kantner around this time, so it was most likely a shared riff.
If you check out the PERRO sessions from January 1971, there's one quick & basic instrumental which clearly starts with the same chord progression: https://www.youtube.com/watch?v=qFGY8v2l3Og 
The theme popped up again a year later in the Dead's 3/5/72 show. Kantner and his Airplane crew recorded 'Your Mind Has Left Your Body' in Nov/Dec '72, with Garcia and Mickey Hart: https://www.youtube.com/watch?v=EzmRuwhNqWI 
So the jam was being played long before the song was recorded. The connection has been disputed since - commenters have pointed out similar riffs in other songs - and as Phil said, "it's just four chords." (He decided to call it the "Mud Love Buddy jam" in the Dick's Picks 12 release and denied that it had any name or origin.) But I think Garcia's slide playing in the jam is eerily similar to his pedal-steel playing in the studio song; and the name is quite appropriate, so the Mind Left Body tag has stuck. Most of the times it was played, Garcia's delicate slide playing resembled the Goin' Down the Road instrumental in somehow combining feelings of grief, bliss, and transcendence.

Its first appearance in a Dead show was in the 3/5/72 Good Lovin', one of the great versions of Good Lovin' from that year; while Pigpen raps, starting around 6:30 they slip in and out of the melody, which is performed much like it will be in '73, with Garcia on slide and Weir playing fingerstyle.
http://www.archive.org/details/gd72-03-05.sbd.miller.20739.sbeok.shnf

It was then used again in the awesome finish to the 4/8/72 Dark Star, but with a totally different feel; at some shows their creative intuition is so high they can take familiar themes and transform them into something new, and here the chords are blended into a 'happy jam' at Sugar Magnolia-tempo, one of their finest moments.
(Now included on the Steppin' Out set, though I preferred the sound of the old tapes; reviews-only at http://www.archive.org/details/gd72-04-08.sbd.giles-jeffm.2534.sbeok.shnf )

(A similar moment comes at the end of the 3/23/72 Dark Star, when they enter the Feelin' Groovy jam that was a frequent part of Dark Star for years; but in this Star it's combined with other elements and turned into a Sugar Magnolia-type jam.)
http://www.archive.org/details/gd72-03-23.sbd.goodbear.137.sbefail.shnf (there's also a Miller source)

The Mind Left Body theme makes another appearance to conclude an equally triumphant Dark Star on 9/21/72; this is one of the most forceful, uplifting versions, and very different from how they played it later.
(Dicks Picks 36; reviews-only at http://www.archive.org/details/gd72-09-21.sbd.masse.7296.sbeok.shnf )

It then took exactly a year-long break, as far as I know, until popping up again at the end of the 9/21/73 Other One. Garcia starts it with a repeating riff, and here the band plays a rather brief undeveloped version in a rollicking upbeat style, before going back into the Other One theme.
http://www.archive.org/details/gd73-09-21.sbd.miller.17410.sbeok.shnf

As they started the fall tour, their jams became much 'deeper' than they had been, and in the 10/19/73 Dark Star they take the audience on quite a journey. After the verse, they go into a rather threatening space in which Lesh plucks deep notes while Weir gently strums beneath him, and Garcia makes melancholy wah-wah sounds. But the sad feeling lifts as the Mind Left Body theme starts; they develop it at length, with Garcia playing different variations on the melody, first on slide and finally in fingerpicking style - this is a top version. From there they go into a strong 'tiger jam', and drop again into an introspective space. Overall there's a very heavy feeling with some striking transitions in mood; this is the approach they'd take in their jams for the rest of the year.
(Dick's Picks 19)

The 10/25/73 Dark Star starts with some ominous bass rumbles to announce the impending journey. (Interestingly, the next few Stars also start with little bass solos, perhaps to settle the audience down or set the mood.) This time the Mind Left Body theme comes near the start of the Star - after a few minutes of noodling, Weir starts the chords using the 'phased' guitar tone that he'd normally use for this jam. Garcia picks gently at it for a couple minutes, but this time it doesn't have the shifts in mood, and they just drift out again; usually they bring the Mind Left Body theme up at the end of a long jam, and here perhaps it was too early in the jam to carry any weight. But they make up for it; immediately after the verse, a deep Space ensues with some huge feedback screeches from Lesh, so it's quite a jolt (or relief) when the jaunty Eyes chords start up.
http://www.archive.org/details/gd1973-10-25.set2.sbd.cribbs.34837.sbeok.flac16
( http://www.archive.org/details/gd73-10-25.sbd.vernon.14451.sbeok.shnf has more reviews, but is lesser quality)

The 10/30/73 Dark Star is very slow and deliberate; though not as famed as other Stars on this tour, it's very good and heavy. This time they're deep into the Star before Garcia starts the Mind Left Body theme with fingerpicked chords, and the rest pick it up immediately. There's a difference here: usually after the four descending chords, they do an extended 'grounding' chord (just as in the China>Rider 'Groovy' bridge), but here they stick to the four chords. They also slow down, with Garcia switching to slide, and it becomes a very slow, sad version which goes into the Dark Star theme. After the verse, they again slow down into near-silence and spacy dribblings; Lesh hints at Stella Blue, but Garcia decides to stay in space for a while before finally starting Stella.
http://www.archive.org/details/gd73-10-30.sbd.powell.16818.sbeok.shnf (there's also a Miller)

The 11/11/73 Dark Star is justly revered as one of the best; it's definitely a super version with some fantastic playing. At the conclusion, as they drift around in a frenzy, Weir blazes into a very fast Mind Left Body. Garcia is eager to play, and the band is hot and creative, giving this jam a joyous effect similar to the '72 Stars - another top version. Unusually, they give the theme an actual 'ending' this time, like a song, before starting Eyes. It's also interesting that from now on, the Mind Left Body theme moved out of its usual place in Dark Star and could be found in any of the second-set jams; it was used in only one more Star.
(Now available, finally, on the Winterland set; reviews-only at http://www.archive.org/details/gd73-11-11.sbd.schlissel.14105.sbeok.shnf )

11/20/73 has a fine jam, with Truckin'>drums & bass>Other One. After the 'tiger jam' which is often the signal for things to start winding up, Weir starts the Mind Left Body chords and they play a quick, fast version; Garcia's notes are keening as usual, and after a few passes they go into Stella Blue.
http://www.archive.org/details/gd1973-11-20.set2jam.matrix.vernon.83165.flac16 (among others)

12/2/73 is famous for its meltdown; in an already-unusual set, the Playing in the Band seems steady enough until all hell breaks loose onstage and unearthly shrieks and groans flatten the audience and subdue the music into ashes. But from the silence, Garcia softly fingerpicks the Mind Left Body chords and they lift spirits again with a long, beautiful version that is somehow simultaneously sad and joyful.
http://www.archive.org/details/gd73-12-02.aud.vernon.17278.sbeok.shnf (SBD on Dick's Picks 14)

12/18/73 features a Dark Star jam coming out of the Weather Report, which I think they'd done just once before on 11/30. This one is very sweet and jazzy; Garcia hints at the Mind Left Body first, and they enter a rather short 'alternate' version of the theme, with the four chords played in a different rhythm. It's mostly a Garcia/Weir duet, since Lesh is very quiet and doesn't seem to be adding anything. When he comes in, he's thinking of going into the Other One, but they continue with Dark Star; after the verse he has his revenge, bombarding the audience with some alarming feedback which builds until the whole band are playing loud, hair-raising screeches. Garcia & Weir then quiet things down again, playing a gentle melody which seems like it might lead back into the Mind Left Body theme (see note), but instead they stop for a drum solo.
http://www.archive.org/details/gd73-12-18.sbd.hamilton.12214.sbeok.shnf

(The melody Garcia starts playing but aborts is familiar from a couple other Dark Stars - the mighty version from 12/6/73 in which he plays the lilting riff repeatedly while Lesh booms out galactic Feedback; and the end of the 2/24/74 Star where a similar riff is played at length, to great effect.)
http://www.archive.org/details/gd73-12-06.sbd.kaplan-fink-hamilton.4452.sbeok.shnf
http://www.archive.org/details/gd74-02-24.sbd.windsor.199.sbefail.shnf

The Mind Left Body theme continued its progress in 1974, a year in which the jamming reached a new level, with the Dead flitting easily from theme to theme. It first appeared in 5/12/74, a show with a very fine Other One>jam. (I think it's underrated in the reviews.) Here the Mind Left Body finds its usual place at the end of the jam, and is a standard version with Garcia on slide; but Keith is playing very discordantly, which seems to distract the others, and they stumble into Row Jimmy.
http://www.archive.org/details/gd74-05-12.sbd.sacks.2224.sbeok.shnf

5/19/74 has a classic Truckin' jam which goes through many themes. Lesh wants to start Not Fade Away, but Weir has other ideas and starts the Mind Left Body. Though Garcia is on slide again, he has a distorted tone this time, which gives the jam a different edge; Weir plays the chords in a staccato way, and they quickly turn it into a funk jam which segues smoothly into Not Fade Away.
http://www.archive.org/details/gd74-05-19.sbd.clugston.6957.sbeok.shnf

6/16/74 has another Mind Left Body jam, closing the jam out of Truckin'. They ease into this one a little uncertainly, so it's a rather loose and playful version, not as emotive. Garcia plays a waspy slide while Godchaux clatters around on the Fender Rhodes, and they segue smoothly into Wharf Rat.
(Road Trips vol. 2 no. 3, bonus disc, track 6)

6/28/74 is renowned for its half-hour jam coming out of the Weather Report. Much of it is a Garcia/Weir duet with Lesh sitting out for some reason, like some of the '83 spaces. The Mind Left Body theme comes up not long into the jam, with Garcia playing a similar chord variation in his 'watery' tone, and Weir joining in with the familiar chords. This is a very long, top version, with Keith adding some xylophone-like chimes. Then they veer into a Dark Star direction....
http://www.archive.org/details/gd74-06-28.moore.weiner.gdADT18.16038.sbeok.shnf (SBD on Dick's Picks 12)

7/31/74 has a very hot Truckin' jam that travels far and wide. Garcia rips into the Mind Left Body chords; it's a long, bouncy, upbeat version, and Garcia doesn't want to let go, so he continues it with a kind of quasi-Mind Left Body variation for a while, playing almost Chuck Berry-style. Finally the band slows down and Garcia turns on his 'watery' tone, seemingly laid-back until they start sliding into the Spanish jam - this becomes pretty remarkable, as Garcia plays a 'tiger' while the rest of the band is doing the Spanish jam! Then they go back into the Mind Left Body jam again briefly, before settling into Wharf Rat. There were only two shows in which the Spanish and Mind Left Body jams were combined like this.
http://www.archive.org/details/gd74-07-31.sbd.ziggy.1019.sbeok.shnf (sbd - there's also a Miller)
http://www.archive.org/details/gd74-07-31.degen.weiner.gdADT.7363.sbeok.shnf (aud)

9/14/74 has another of the long Truckin' jams common to that year; it has a short version of Mind Left Body at the end, which they keep slowing down until it segues into Wharf Rat.
http://www.archive.org/details/gd1974-09-14.28353.sbeok.flac16 (set 2 w/ reviews)
also http://www.archive.org/details/gd74-09-14.sbd.miller.30653.sbeok.flacf (aud/sbd)

(On 9/18/74, in the first couple minutes of the Caution jam, Weir is playing the Mind Left Body chords, though the others aren't really following him.)
http://www.archive.org/details/gd1974-09-18.sbd.miller.20675.shnf

On 10/17/74 they blended jam themes again in a long Other One, first doing the Spanish jam with Garcia on slide, and then merging seamlessly into the Mind Left Body in the same tempo. It's a good version, with Lesh adding some nice bass runs.
(Now available on the Grateful Dead Movie CD set, in echoey sound, and also on the bonus DVD.)

The Mind Left Body theme wouldn't fall silent for long - just a few months later, it became one of the building-blocks for The Music Never Stopped, as heard clearly in the jam at the end of track 11 here:
http://www.archive.org/details/gd1975-02-28.sbd.smith.93779.sbeok.flac16

Occasionally in the '80s and '90s, the theme would recur in a few shows - but that's a story for someone else to write....

*
Postscript - One reader comments -
A few sightings of the MLB jam post-'75:

- In 1976, the MLB theme showed up in the end jam of The Music Never Stopped a few times. In particular, check out the 9.30, 10.2, and 10.3.76 performances.
- In 1978, the MLB jam became intertwined with Weir's interpretation of Got My Mojo Workin' a couple times. These jams would have the descending 4 MLB chords as the first part of the jam, with the Mojo theme in the place where the rocking second part of the MLB jam had been in '73-'74. Check out 10.18.78 out of space (in the Mojo jam) and late in the 10.22.78 Not Fade Away.
- On 9.6.79 the MLB jam made its last '70s appearance; Garcia plays the theme as the intro to Stella Blue.
- In the '80's and '90's, the MLB jam showed up usually with only the first part of the jam recurring, sometimes with bandmembers also riffing on Dear Prudence. Some examples include 11.29.81 out of He's Gone, 12.30.83 out of Space, 3.10.85 out of Smokestack Lightning, 3.22.85 out of Terrapin, 3.24.90 out of Terrapin, 8.17.91 briefly before drums, 9.25.91 out of Space, 6.8.92 out of Corrina, and 3.10.93 out of Corrina.
I'm sure there are others that aren't listed here... There is another list of Mind Left Body appearances in the comments below.