The place a Reverend Mother dare not look is the ancient force that "takes"
Masculine and Feminine are broken down into a more fundamental concept, Creation and Destruction. Looking inward to the force opposite your gender will be "overwhelming."
<PERSON> said, "There is in each of us an ancient force that takes and an ancient force that gives. A man finds little difficulty facing that place within himself, where the taking force dwells, but it's almost impossible for him to see into the giving force without changing into something other than man. For a woman the situation is reversed."... "These things are so ancient within us that they are ground into each separate cell in our bodies, we are shaped by such force. You can say to yourself, yes I see how such a thing may be, but when you look inward, and confront the raw force of your life unshielded, you see your peril. You see that this could overwhelm you. The greatest peril to the giver is the force that takes. The greatest peril to the taker is the force that gives. 674
It's as easy to be overwhelmed by giving as it is by taking.
what is the force that takes? (relating to physics)
The B.G. ability to see into maternal ancestry is a product of awakening to the "giving" force. A Reverend Mother can see the succession of bio-reproductive creation which culminated in her birth, giving them an unparalleled understanding of the past. Prescience, a common thread in dune, is the cognition of the future. Quite the opposite of other memory which deals only in the past. In physics, Entropy is the destructive force which moves a system from ordered to disordered. To glimpse the future is to see death and destruction of the present (reason why it's frightening). A few times in Dune, it is said that "time becomes space." Observing possible futures would take an understanding of the possible paths entropy could take on it's journey to the entropic heat death of the universe. To understand the future you must understand destruction. It's a reasonable postulate that the "force that takes" is the root of prescience, which <PERSON> (nearly) masters after drinking the water of life. 283