What is the origin of the Bene Gesserit's powers?

Question

Where did the Bene Gesserit's powers come from?

Answer 1

The origins of Bene Gesserit are covered in the Anderson/Brian Herbert prequel "Dune: The Battle of Corrin".

The order was started by Raquella Berto-Anirul, who was the first Reverend Mother.

• Her powers originally were caused when she was infected during Rossak Epidemic, and was treated with water that was infused with native Rossak plants. That combined with the virus altered her so that she had cell level control and could control chemical reactions in her body.

  Sounding apologetic, Jimmak said, "We put you in the healing water. My friends and me. Let you soak for a whole day. It washed away your fever."

  "Healing water?" Raquella realized that she did feel strangely energized.

  "Special place." He smiled. "Only the Misborn know it."

  ...

  From the blood samples, he {{Dr Suk}} concluded that something peculiar had happened inside Raquella's body, a biochemical transformation he had never seen before. The battle between the retrovirus and the strange chemicals in the cenote had done something to her biochemistry, changing her in fundamental ways.

• Those powers manifested when Supreme Sorceress Ticia poisoned her with "Rossak Drug":

  She was already lost, drifting into dark unconsciousness. Suddenly light flared in her mind, showing Raquella a new way to fight back, a weapon she had not known she possessed. Her body had been altered in the crucible of the Scourge, after assimilating the incomprehensible mixture of environmental chemicals. Raquella had unexpected skills and new resources now, deep within her very cells.

  Utter calmness pervaded her, and in her mind's eye Raquella saw the connections that led from the core of her brain—neural pathways spreading outward to veins, tendons, muscle—governing every function, whether voluntary or automatic. All so clear, like a human blueprint. ...

  During this event she also came up with the beginnings of the infamous "Fear" litany:

  "I will not give up," she murmured. "I will fight back. Only fear can kill me now."

  Going deep within herself, Raquella waged an internal war.

  She shored up her body's defenses and constructed a biochemical wall against the poison's attack. Then she confronted the enemy head-on. Analyzing the molecular structure of the Rossak drug, she shifted the elements around...

  ... Because she was doing this for the first time, she explored her abilities, and realized that she had complete control over every cell and extraneous molecule in her body. ...

• She was also (independently) the first person who realized the medicinal properties of spice melange, alongside with her husband M. Suk (the founder of Suk medical school seen in Dune).

• She started the order from the Sorceresses of Rossak, who themselves had unusual mental powers AND started the concept of breeding program:

Ticia gave him a withering look for interrupting her. "...Now, in the face of this sweeping epidemic, I point out that we Sorceresses have another area of expertise. Because of our harsh world and our precise records of breeding over many generations, we understand bloodlines, the most important raw material of the human race. If this Omnius Scourge grows worse, we could lose prime branches of our species—not just the sheer casualties, but paths to our future.

"Now, as whole families, whole cities, are devastated on world after world, we cannot react too soon or too vigorously. Our race is in extreme peril. Even as we struggle to find a cure for this foul biological weapon, we must also take drastic action to preserve the best DNA before it it lost forever—protect and store key markers of some of the strongest lines, or the disease may erase them entirely. We must establish a program to protect the genetic information of all people, on all planets." She lifted her chin. "We Sorceresses have the capacity to manage such a program."

Answer 2

From the actual source (as opposed to the ugly books written after Herbert died)

From The first Passage:

"I've studied with Thufir Hawat."

"The Great Revolt took away a crutch," she said. "It forced human minds to develop. Schools were started to train human talents."

"Bene Gesserit schools?"

She nodded. "We have two chief survivors of those ancient schools: the Bene Gesserit and the Spacing Guild. The Guild, so we think, emphasizes almost pure mathematics. Bene Gesserit performs another function."

"Politics," he said.

"Kull wahad!" the old woman said. She sent a hard glance at Jessica.

"I've not told him. Your Reverence," Jessica said.

The Reverend Mother returned her attention to Paul. "You did that on remarkably few clues," she said. "Politics indeed. The original Bene Gesserit school was directed by those who saw the need of a thread of continuity in human affairs. They saw there could be no such continuity without separating human stock from animal stock - for breeding purposes."

And Later in the first passage:

"Have you ever seen truthtrance?"

He shook his head. "No."

"The drug's dangerous," she said, "but it gives insight. When a Truthsayer's gifted by the drug, she can look many places in her memory - in her body's memory. We look down so many avenues of the past . . . but only feminine avenues." Her voice took on a note of sadness. "Yet, there's a place where no Truthsayer can see. We are repelled by it, terrorized. It is said a man will come one day and find in the gift of the drug his inward eye. He will look where we cannot - into both feminine and masculine pasts."

And much, much later:

Jessica shook her head, seeing the signs of disturbance in Harah's face. What have I borne? Jessica asked herself. A daughter who knew at birth everything that I knew . . . and more: everything revealed to her out of the corridors of the past by the Reverend Mothers within me,

"It's not just the things she says," Harah said. "It's the exercises, too: the way she sits and stares at a rock, moving only one muscle beside her nose, or a muscle on the back of a finger, or - "

"Those are the Bene Gesserit training," Jessica said. "You know that, Harah. Would you deny my daughter her inheritance?"

Answer 3

In universe answer from hyperaware character Norma Cenva: "Crisis and Survival"

Cioba Venport: "You have changed yourself into something more than human, Norma. I trust you are aware the Sisters of Rassak, including the last few Sorceresses, are also attempting to enhance themselves through drug induced traumas, near death encounters. Do you think there are any similarities with the navigator transformation?”

Norma Cenva: "All key advancements occur though crisis and survival. Without stress and extreme challenge, one cannot meet her potential."

The Bene Gesserit unlock mental powers from pushing the limits of survival by placing students in crisis situations. One such crisis is the Spice Agony, which is the source of a Reverend Mother's "other memory" ability. The testing of the box is another crisis situation.

For the Sorceresses of Rassak, their crisis was being a developing fetus amongst the fierce pathogens of the jungle world.

Other Bene Gesserit abilities, such as the voice, do not require undergoing the reverend mother agony. This is proven by Paul using the voice in the thopter and Gaius Helen Mohiam suggesting he learn it.

The Bene Gesserit mental powers are derivative of survival necessitating evolution.