The sixth hour is the hour of the sacrum
In her 1975 Boulder advanced class, working through the sixth hour with senior practitioners, Ida pressed the room on why the rotators matter. The students offered partial answers — that the rotators balance the legs under the pelvis, that they contribute to pelvic-girdle rotation. Each answer was accepted as partly right. The answer she was waiting for came when someone finally named the sacrum. The rotators attach to the anterior surface of the sacrum, and this attachment makes them the one route by which the practitioner can reach the front of the sacrum without going inside the body. The sixth hour, in Ida's framing, is built around exactly that opportunity. Everything earlier in the recipe has been preparation; the sixth hour is when the work finally lands on the bone she considered the most positionally significant in the body.
"that this is a unique situation where you can get the prevertebral organization of the sacrum from the outside of the body. And you just, any of you that want to, offer me a suggestion as to what single bone of the body and its position is more important than the sacrum."
Ida pulls the discussion of the rotators back to its real target — the anterior sacrum.
The claim that the sacrum is the most positionally important single bone in the body is not a casual one in her teaching. She returns to it across years. The sacrum sits at the floor of the spine and at the back of the pelvis simultaneously; it is the structural pivot where the trunk transmits its weight into the legs and the legs transmit their support into the trunk. When the sacrum is mispositioned, the lumbars cannot lengthen, the pelvic floor cannot horizontalize, the spine cannot pump the cerebrospinal fluid, and the nervous plexi that determine pelvic metabolism cannot fire cleanly. The sixth hour exists in the ten-session series specifically because by that point the practitioner has prepared every neighboring structure and finally has a chance to confirm the bone itself.
"coccyx, So the sixth hour is really the hour of the sacrum. Can you balance those that sacrum by virtue of organizing the piriformis basically the obturator in the second place which does the inside of the pelvis not really to the inside of the sacrum."
She closes the conceptual frame of the sixth hour by naming the two muscles that do the work.
Why the rotators are the route in
The architectural logic Ida wanted students to grasp was that the piriformis spans from the anterior surface of the sacrum out through the sciatic notch to the greater trochanter. Releasing the piriformis therefore pulls on the sacrum from the front — but from outside the body. There is no other structure that offers this access. The psoas runs in front of the lumbars but does not attach to the sacrum proper; the obturator works the inside of the iliac surface but not the sacral face directly. The piriformis is the unique tool. In the 1975 Santa Monica advanced class, Ida pressed Danny and the room to articulate this relationship and refused to let the students settle for vague accounts.
"Well, generally, the rotators, of course, affect the rear back part of the sacrum. Anybody wanna Danny? It seems that a shortening of or a constriction in rotators, especially in my mind, see the piriformis sucking that sacrum over to one side or the other. If it's and well, imbalancing the sacrum because of its direct pull right on the sacrum."
Pressing Danny to name why the piriformis matters more than the other rotators.
The pedagogical insistence here is worth noting. Ida did not want students to learn that the rotators are important in general; she wanted them to feel why the piriformis specifically holds the leverage to position the sacrum. The exchange continued when Jim added that the piriformis spans the ilium and extends into the sacrum. Ida accepted the addition but kept the focus on the unique attachment. This is the operative architecture of the sixth hour: the practitioner reaches the anterior sacrum through the back of the pelvis, by way of a muscle that originates on the bone she most wants to move.
"The real goal of working up the back of the leg is to get under the Ruleus. That's right. That's right. And this then is going to be the first hour where we have some hope of getting at the anterior aspect of the sacrum by working externally with the insertion of the rotator which arises in it. That's right. And you see all of this once again is a positioning of the pelvis. Obturator will have the inside of the iliac, the ischial aspect of the iliac. But the whole thing then makes a brand new decision."
Speaking on the public tapes, she states the goal plainly.
The coccyx determines what the sacrum can do
In the 1975 Boulder class, after the rotator discussion had moved through its full arc, Ida turned to a structure students chronically underweighted: the coccyx. Her position was unambiguous. The sacrum cannot be released while the coccyx is pulled forward, because the ligamentous connections between them keep the sacrum on strain no matter what is done to it directly. The coccyx, in her teaching, is the tail end of the lever; until it is positioned, the rest of the lever cannot find its balance. This is one of the points where her advanced-class teaching pressed beyond what students had absorbed from the basic training, and she returned to it across multiple years.
"about the position of the coccyx. And the position of that coccyx is going to do a very great deal in determining the extent to which you're going to be successful in, quote, horizontalizing your pelvis. It will be very important so"
She names the coccyx as the determinant of pelvic horizontality.
The order of operations she taught was specific. The practitioner addresses the rotators first, then — having found that the rotators alone do not finish the job — leaves the rotators and goes to the coccyx, and only after the coccyx has been organized as well as possible does the practitioner return to the sacrum. This sequencing is itself a teaching beat: you do not stay on a structure that is not yielding; you leave it and address its determinant, then come back. In the second half of the same passage, Ida walks through this sequence and lands on the image of the ilio-sacral junction as a small mountain range — the heaping of tissue she found on nearly every body she touched.
And the position of that coccyx is going to do a very great deal in determining the extent to which you're going to be successful in, quote, horizontalizing your pelvis. It will be very important so that you deal with that coccyx at this point having dealt with the rotators and having found that you're not happy with the rotators and you don't just climb on the rotators and stay, you get off the rotators and go and look at the coccyx and see what effect this has on you. And having done as well as you can in organizing that coccyx, then you go and look at the sacrum."
She lays out the full order of operations from rotators through coccyx to sacrum.
The image that closes that passage — the ilio-sacral junction as a small mountain range — became one of her durable teaching shorthands. She used it to name a finding her fingers met on nearly every body: a heaped, jammed band of tissue where the ilium and the sacrum had been pressed together over years of misaligned movement. The image is doing more than description. It is naming the clinical reality that students would have to confront in the sixth hour, and it is preparing them not to be surprised by what they found there.
"And the Sacroiliac Junction is marked by a small mountain range."
The image she leaves the room with.
Releasing the coccyx releases the sacrum
In a 1971-72 mystery-tape session, Jen pressed the question of how the pelvic-floor fascia ties into the coccyx, the sacrum, and the sacrotuberous ligament. Ida used the moment to state the dependency relationship directly. The coccyx and sacrum are connected by ligaments that run in both directions, but the determining bone is the lower one. When the coccyx is held forward, the sacrum is strained, and direct work on the sacrum cannot resolve the strain. Work on the coccyx, however, does release the sacrum. This is the asymmetry that justifies the order of operations she taught.
"Well you see when that coccyx is still pulled forward, the sacrum will be on the strain no matter what. Releasing the sacrum won't release the coccyx as much as releasing the coccyx will release the sacrum, at least as I see it."
She names the asymmetry between coccyx and sacrum.
The conversation continues with Jen describing the gluteal fascia wrapping the coccyx and the sacrotuberous ligament running into the sacrum. Ida used the moment to give students a frank account of what the work actually requires. The fourth hour, in her account, demands getting into the ligaments that attach to the coccyx and the sacrum — work that students find scary and that clients find scary too, because it is a long way into the body. But there is no substitute. The body has to be stood on its bottom, and the bottom has to be organized first.
"And the coccyx determines the floor of the pelvis. Well, it's quite true, it's the second segment of the coccyx, as I remember. In other words, it's way high and the floor of the pelvis doesn't follow as far askew as the coccyx itself goes as your fingers tell you. But all of this is a very important consideration for you that to get in there, you have to get to the ligaments that relate the coccyx, the sacrum, and the STI. Now this is a little bit of a terrifying business to you junior people. That's a terrible long way to be into a person. And it's a scary way."
She levels with the junior practitioners about the depth of the work.
The ilio-sacral junction: the small mountain range
The heaping of tissue at the superior aspect of the ilio-sacral junction was something Ida and the senior practitioners agreed they found on nearly every body. In a 1971-72 mystery-tape exchange, a student observed the universality of the finding and asked why. Ida's answer drew on her broader theory of fascial behavior. Ligaments that are consistently moved in an aberrant pattern wind-shorten; they lose their resilience and become bristle-like. Without the alternating stretch and recovery that produces pumping action across the ligament, nutrient fluid does not penetrate, and instead of resilience the practitioner finds heaping.
"so there's going to be a ligament between this sacrum and the fifth lumbar, and there's going to be a ligament between the sacrum and the Mhmm. Femurisine. This now, as the body is consistently moved in an aberrant pattern, some of those ligaments are going to consistently shorten and some of those ligaments are going to get more bristle like."
She explains why the ilio-sacral junction heaps on nearly every body.
The same exchange registers Ida's frustration with sclerotherapy and similar approaches that work on the ligaments without organizing the body around them. She acknowledged that sclerotherapists concentrate on these very ligaments and that their work, in itself, is fine. What is missing, in her account, is the structural ordering that would let the ligaments hold their new length. Without that, the body returns to its prior pattern. The structural integration practitioner's task is to make the released ligament part of a new pattern of relationship — not just looser, but in its proper position within a reorganized whole.
"Now making orderly, those ligaments, sacral relaxants, forth, is really organizing them in space. They've got to be the righteous to support rather than jailed together. The sclerotherapists concentrate a lot on those ligaments to try to corroach them. Sure, and all of this is fine and all this, what's What's the rest of it? You all know. It's a gavage massage. All of this is fine, but nobody orders it. Nobody puts it in the pattern that it was designed for."
She situates the ligamentous work within the larger project.
Floating the sacrum so the lumbars can come back
The phrase Ida and the senior practitioners used for the result of well-done sixth-hour work was that the sacrum begins to float. By float they meant something specific: that with each inhale the base of the sacrum can move backward, separating from the fifth lumbar, while the apex moves forward; and with each exhale the motion reverses. This is the pumping action Sutherland described in cranial osteopathy, but Ida insisted that it could not occur without sacral mobility — and that without it, the cerebrospinal fluid did not in fact pump. The sixth hour, in this framing, is the hour that turns the spine into a working hydraulic system.
"The sixth hour is dealing with ultimately the sacrum and trying to or accomplishing this floating of the sacrum so the lumbar vertebra can become more as lumbar vertebra become more posterior and flatter, the sacrum in helping the tip turns further under."
She accepts and modifies a student's description of sacral floating.
She corrected the student gently on one point. Whether the apex of the sacrum turns under or stays where it is depends on where the bone has to go in terms of the body's balance — not on a universal rule. Many sacrums whose coccyges have been pulled hard under do not need further tucking; they need a different position entirely. The teaching beat here is that the floating sacrum is not a stereotyped end-state but a recovered capacity for movement, and the movement itself is what allows the lumbars to find their length.
"I like to add on that sixth hour yesterday. I felt this so much when you finished working on me is the floating and sacrum in respiration that's tied in with the respiratory function. Now what is this floating sacrum in respiration business? That when the sacrum is more organized that with the normal inspiration breathing the lumbar spine is able to straighten and the base of the sacrum can come out and the tip of the sacrum rotate in. So it tends to straighten the spine of each breath."
Don describes the floating sacrum he felt after his own sixth hour.
The honesty of that refusal is characteristic. Ida had a clear mechanical picture of what good sixth-hour work produced, but she did not pretend to know which direction the causation ran between sacral movement and respiratory movement. What she insisted on was the observation: when the sacrum is free, the breath goes down into it, and the spine pumps. This was the milepost she taught students to look for at the end of a successful sixth hour.
"I said normal respiration and in view of the fact that the spine is held more or less to an effective length. If you're going to get movement up and down that spine, what has to happen? The sacrum has to bow behind that. And this is what it does. As you inhale, the apex of the sacrum dives forward in order to let the base of the sacrum come back, in order to separate from the fifth lumbar, in order to separate from the fourth lumbar, in order to separate from the third lumbar, you just carry it along. And in the sixth hour, if you have done your stuff, you are then able to unhook the hook that's up in that dorsal put there by the fact that you were not lengthening your spine in respiration. Now this is the real function of the sixth hour. And the milestone that tells you you've gotten where you should be is the fact that that sacrum is moving with every breath. If you haven't, there's something that you haven't done. Now what is it? How do you really reach the sacrum? How do you really reach the front of the sacrum? And that's the one way you can get to it. And how do you get to the piriformis?"
She names the milepost that tells the practitioner the sixth hour is done.
What the pelvic lift does at the sacrum
Before the sixth hour, the practitioner has already been working on the sacrum without naming it as the target. Every pelvic lift performed across the earlier hours is, in Ida's framing, a sacral effort. The lift separates the lumbars, lengthens the soft tissue overlying the sacrum, and reorganizes the fourth-to-fifth-lumbar and fifth-lumbar-to-sacral articulations. But it works on the sacrum from above and from behind. The sixth hour is the first hour where the practitioner addresses the bone from in front of it.
"And that pelvic lift is a turning down of the sacrum, a separation of the lumbar vertebrae so that they can begin to straighten out. You have seen and you will continue to see short lumbars and necessarily if you have a short lumbar you are going to have that reversal of the sacrum. This being the base and this being the apex. The apex will be back, the base will be in and the lumbar will be short. And as you lengthen the lumbar and bring them back, this has to happen, there is no way nothing else can happen. And this is what you are accomplishing in your pelvic lift. You are organizing every one of those lumbar articulations but particularly fourth to fifth and fifth to sacral."
She walks through what the pelvic lift accomplishes at the sacrum.
In the same passage she described the stringy muscles that overlay many sacrums and the bone underneath that feels, as she put it, about like the rock of Gibraltar. The first task is to give those overlay muscles enough elasticity that the underlying bone can begin to participate in the body's movement. Only after that elasticity is restored can the practitioner expect the cervical curve and the lumbar curve — those reciprocal secondary curves she returned to often — to find their balance against each other.
"And so you suddenly find that what you have really been doing is straightening that spine from one end to the other. The guy stands up says, why I feel so much straighter. Of course, he feels straighter. He is straighter. He made him that way. He made himself that way. Because all the way along the line, you have been demanding from him the kind of movement which as you held the muscle and the fascia organized, he organized himself. But what you have to know is how to hold it, where to put it, what commands to give him to get him to do it. Now the Lord has been very, very good to me this summer."
She names the reciprocal relationship between cervical and lumbar curves.
Why earlier hours haven't gotten in around the sacrum
On the RolfB5 public tape, Ida set up the sixth hour by asking the room what they had not yet reorganized in the pelvis after five hours of work. A student named the answer: the practitioner has not gotten in around the sacrum. Ida accepted the answer and used it to teach a structural point that students often missed. Pelvic lifts can address the sacrum from above, and side-lying work can address it from the lateral surfaces, but the anterior surface of the sacrum has remained out of reach. The base of the sacrum may still be tipped anteriorly, the apex may still be skewed — the bone is better than when the work began, but it has not yet been the dedicated focus of any hour.
"You haven't gotten in around the sacrum? Is that what you said? You're absolutely right. You haven't gotten in around the sacrum. And in many instances, in spite of all your pelvic lifts and so forth your sacrum as a whole is still anterior."
A student names what the earlier hours have left undone.
The reason this matters, in Ida's account, is not merely structural. The sacrum is the bony housing for the lower autonomic nervous plexi — the structures she said were the real determinants of pelvic-organ function. The floor of the pelvis matters mechanically, but it does not house the plexi. The sacrum does. The sixth hour, in her framing, is therefore not only the hour that completes the pelvic geometry; it is the hour in which the practitioner's work begins to reach the autonomic structures that govern what happens inside the pelvis.
"And you better get it done because you've been going around and around and around and around. Around And you've been talking about the floor of the pelvis as being so important, and it is. But you see, the floor of the pelvis does not have to do literally with the plexi, the nervous plexi, which are the important controls of that body. Determinants rather than controls of that body. But the sacrum is. And so now it behooves you in trying to put this body together to starve you by getting that sacrum where it belongs. And this will require some more work on the pale end."
She names what the sacrum houses and what the floor of the pelvis does not.
Coccyx, ganglion of impar, and the vulnerable lower pole
Ida's interest in the coccyx extended beyond its mechanical role as the lower terminus of the sacral lever. On the RolfB6 tape, in the course of discussing the autonomic implications of pelvic organization, she pointed to the ganglion of impar — the small, unpaired autonomic ganglion that sits at the junction of the coccyx and sacrum. Its position, she observed, is anatomically vulnerable. Falls onto the tailbone are common across a life; the ganglion is exposed to direct impact in a way that most autonomic structures are not. The practitioner who expects to organize a body has to be alert to what damage at this site may be contributing to the symptoms presenting elsewhere.
"And you remember we spent a lot of time yesterday talking about the urgent importance of the coccyx in this project. And we talked spent a lot of time discussing the fact that the sacrum that the coccyx the position of the coccyx, the relation of the coccyx to the sacrum, all of this determines the floor of the pelvis, determines the adequacy of the relation of the nervous plexi that control the metabolism through that pelvis. We also discussed, fairly at length, the autonomic nervous the autonomic nervous system, and the fact that the lowest plexus there is a single plexus, the ganglion of empire. And that ganglion lies in a place which is quite vulnerable, you see. All through your life, you are subject to falling on your little tail end. It's quite vulnerable. And if you expect to know how to organize a body, you have to be very well aware of the problem of this with toxics, the role of the ganglion, and you have to be alert for the role that the ganglion may be playing in the symptoms that this individual presents. And these symptoms may be anything, including heart disease."
She locates the ganglion of impar and explains its vulnerability.
The coccyx, like the sacrum above it, can be rotated as well as tipped. In a 1973 Big Sur session, Ida and her colleagues worked through how the coccyx can be pulled to one side by asymmetric tendon shortening. The fingers can detect which side is shorter and can address the asymmetry directly, but the work, like all the work around the sacrum, requires considerable depth and considerable rapport with the client. The practitioner who has not established that rapport in the earliest hours will not be granted access to the coccyx in the later ones.
"The coccyx is the end here and they can also be pulled over to one side or the other and it's all, if it goes one way or the other it's rotated also. It's tied up with tendons but frequently one tendon will be shorter than the other. You can actually go in there and get that coccyx to sit on there a lot straighter if you go in here and work them soft as you're around it."
She describes the coccyx as rotatable, not only tippable.
Where the sacrum sits in the larger arc
Across the public tapes and the advanced classes, Ida positioned the sacrum within an arc of work that began long before the sixth hour and continued past it. The pelvic-lift work of the first hour was already a sacral effort; the leg work of the fourth and fifth hours prepared the structural foundation on which the sixth-hour sacrum could float; and the seventh-hour neck work confirmed the reciprocal cervical lengthening that the lumbar-sacral changes required. In her own teaching, she circled back from the sixth hour to remind students that nothing in the recipe stands alone — and that the sacrum, more than any other single bone, registers the success or failure of the whole sequence.
"And the fifth hour begins to turn it up in the front so that it has support under the abdominal organs. And your sixth hour, you are still working with the pelvis and balancing that basin. You are now going in primarily to balance the sacrum with the rest of the pelvis. Just as through the entire series, we have never gone where we are working. So here, you don't go where you are working, but you go to the areas that influence the sacral position. Now in order to balance the rotators, one of which is the immediate determinant of sacral position, you have to also give a lot of attention to the hamstrings and therefore and thereby to the back of the legs because everything is connected with everything else, and there's no way of escaping this."
She places the sixth hour within the larger five-to-six-hour arc.
The principle that you never work where you are working — that the immediate target of the hands is rarely the immediate target of the change — is one of Ida's most characteristic teaching beats. Applied to the sacrum, it means that direct sacral work alone will not organize the sacrum; the bone is approached through its determinants, named in order: the hamstrings that have to soften before the gluteus maximus will let the practitioner in, the rotators that hold the bone from in front, the obturator that addresses the inside of the iliac surface, the coccyx that anchors the lower pole. The sacrum is balanced through all of these together.
"Now I want to go back to the fifth hour and look at the fifth hour in regards to what we do in the seventh hour. And that fifth hour, as I see it, is really freeing the lumbar section of the spine, making it independent of the action of the legs by balancing the action of the rectus abdominis and the sulcus. And that's what I look for myself, when I finish that fifth hour that a person can slide those knees up when he's on the bed without disturbing that spine. I have it keeping that spine. Well, have you noticed that if you could only see the knees and the direction in which they took as you asked them to raise, that you would know whether you had this Because if you have balance, the knee will go straight sealing it, at least in the beginning. Beginning right. If you have the balance, you shorten the rectus femoris and fold up."
She names the fifth hour as the hour that frees the lumbar from the legs.
Coda: organizing the bottom
What the sacrum and the SI joint represented in Ida's teaching was not a single technique but a structural premise: the body has to be stood on its bottom, and the bottom — the coccyx, the sacrum, the ilio-sacral junction, the ligaments that bind them — has to be organized before any of the work above can hold. The sixth hour is the hour where this premise is finally confronted directly. Everything before it has prepared the ground; everything after it depends on its success.
"Who worked out, And as you that's when you get an awful lot of other changes too. And, again, you have to have a core built up. And but as you as that person walks in for the first hour, after a while, you can see that sacrum is is tilted one way or the other, and you can see the cock is going the other way. And that's what you have to start thinking about. Now just a minute. I want you to imagine the lumbar fascia pulled too tight and see what it's going to do. Oh, like that. And putting the whole sacrum Right. The base I think we have to move on. It's twenty eleven. And I think it's I think that's most elegant job we've heard done today, and I didn't do any of it."
The image she leaves of how the practitioner reads the sacrum and the coccyx in the first hour.
The position Ida arrived at across her advanced-class teaching can be stated plainly: the sacrum is the most positionally consequential single bone in the body, the coccyx determines what the sacrum can do, and the ilio-sacral junction is where the practitioner finds the consequences of a lifetime of mispositioned movement. The sixth hour exists in the recipe because by that point in the series the practitioner has prepared every neighboring structure and finally has the leverage to address the bone itself — from in front, through the rotators; from above, through the lumbars; from below, through the coccyx; and from outside, through the sacrotuberous and sacrospinous ligaments. When the work lands, the sacrum begins to float, the lumbars come back, the breath goes down into the lower spine, and the body is, for the first time in the series, standing on a base it can support.
See also: See also: RolfA2Side2 — Ida's extended discussion of the iliopsoas and the mechanical relationship between rectus, lumbars, and sacrum, which provides further context for the fifth-hour preparation discussed above. RolfA2Side2 ▸
See also: See also: T1SB (1975 Boulder) — Ida's framing of the first hour as the beginning of the tenth, with implications for how the sacrum's organization is built across the full ten-session arc rather than achieved in the sixth hour alone. T1SB ▸
See also: See also: T10SA and T10SB (1975 Boulder) — additional advanced-class material on the cranial-sacral pumping mechanism and the practitioner's reading of sacral mobility at the end of the recipe. T10SA ▸T10SB ▸
See also: See also: 72MYS101 and 72MYS141 (1971-72 mystery tapes) — earlier discussions of the lumbar lever, ligamentous spanning, and the structural width of the pelvis required for spinal balance. 72MYS101 ▸72MYS141 ▸
See also: See also: B2T10SA and B2T11SB (1975 Santa Monica) — additional rotator and iliacus discussions with Danny, Jen, and the senior practitioners, including the disagreement over iliacus attachments to the sacrum. B2T10SA ▸B2T11SB ▸