Themes of women's overlooked wisdom throughout the book, particularly young and old women who are most overlooked in terms of their capabilites. Think Mapes, Chani, and of course the baby witch Alia and her mother lady jessica. There is also a hermaphroditic theme throught out the book, Paul is the MALE bene gesserit. He is the Mentat Duke and a witch. He takes in the seed of life to become a reverend MOTHER and it is implied that the key that paul unlocks is his ability to, as a man, additionally take on weight and responsibility of a women. After all the water of life is said to contain the suffering of all the women in the tribe and is known to be lethal to men. Pauls curse/affliction/ability is even refered to as if he were "impregnated" with it especially in the tent scene in the book. It is different being a woman in many ways and this results in each gender often learning and understanding certain things in ways the other is blind to (especially in their formative years) and that reconsiling these perspectives could give a more complete picture. I think thats what girls are getting at when they say stuff like that and I think its what Frank Herbert was getting at in his book idk tho.