"in the nature of things" means "according to the way things just are"
"the ground of organic creation" means "the bringing forth of new life" -- in this case, not just babies, but probably crops too (or the author would have specified "new babies" I think)
Women in aboriginal societies seem to have an unspoken
understanding that the way things work is -- the masculine psyche is
secondary to, or removed from, creating new life.
They accept that the fragile male ego requires constant external
reinforcement, and they instigate and support male ceremonies that
shape the male psyche so that it may function positively in nature
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