"Shortening of the Way." This is the label applied by the Bene Gesserit to the unknown for which they sought a genetic solution: a male Bene Gesserit whose organic mental powers would bridge space and time."
The Bene Gesserit hoped to create a male who could survive the ritual spice agony that changes a female acolyte into a Reverend Mother a male thus capable of absolute powers of prescience, able to predict all possible futures and to cause select threads of time to be realized through manipulation. A female Bene Gesserit was limited:
She ... was confronted immediately with a cellular core, a pit of blackness from which she recoiled. That is the place where we cannot look, she thought. There is the place the Reverend Mothers are so reluctant to mention — the place where only a Kwisatz Haderach may look.