As with many discoveries, this one started with a common circumstance but had a curious result. Dr. Rolf, who had extensive knowledge of anatomy, was exploring the painful area with her hands after a sprain. By deep pushing along the line of the tear, she was able to separate the fascia to allow herniated muscle tissue to slip back where it belonged. This reduced the healing process to a few days down from the few weeks a sprain normally takes to heal.
After this experience, she found she could differentiate muscle, bone, fascia, organs and even avoid blood vessels, with practice. She discovered that bound up fascia often restricts opposing muscles from functioning independently from each other. She could separate the bound up fascia manually by deeply separating the fibers. Exactly what shaping of pushing and how deep was necessary to free up this bound-up fascia obviously required extensive knowledge of living anatomy - and extensive training. Without this knowledge, pushing deeply can leave bruises.
As Ida Rolf worked with people, she discovered a link between muscle tension and suppressed emotion. Evidently, when tension is released, some people experience "flashback" memories of the original situations that programmed the need to tense the muscle. There is a sudden release of stored emotion, which in carthartisis clears the need for the tension to be retained. As a result the body returns to its natural posture.
Rolfers often proscribe a certain number of sessions to "unlock" the whole body at once, with a recommended sequence, usually beginning with the muscles that control breathing and the diaphram. Some people believe Rolfing to be painful, others welcome the experience because they enjoy the result.