Footsteps of shamans

"It was the shamans and the medicine man that knew that the woman had to be fertile. She had to already have spilled her first blood, and her fertility was in a particular time in the interval between her monthy losses of blood. This was a secret that could not be divulged to the men, because, if they seized upon this secret, they would have taken away from the Shaman one of the instruments with which to speak to the spirits." -- Back cover.