Houdini knew something about being a coffin-case; could be useful, but not at Harvard, I think.
So how’s this for an instruction of zazen: let the length of the inhalation or exhalation engender the activity in the sartorious and gluteous muscles that rotates the pelvis and extends the hips, and through the extension of the hips let the inhalation or exhalation simultaneously cause the piriformis muscles to act to rotate the sacrum opposite to the pelvis.
Consciousness takes place; the cranial-sacral rhythm acts through the location of consciousness to open an ability to feel. Houdini developed an ability to feel things that most people don’t feel, related to the movement of breath; that’s how he managed to survive being sealed in a coffin for over an hour.