Marie Carmichael Stopes, Married Love: A New Contribution to the Solution of Sex Difficulties
“ While the ocean can subdue and dominate man and laugh at his attempted restrictions, woman has bowed to man's desire over her body, and, regardless of its pulses, he approaches her or not as is his will. Some of her rhythms defy him—the moon-month tide of menstruation, the cycle of ten moon-months of bearing the growing child and its birth at the end of the tenth wave—these are essentials too strong to be mastered by man. But the subtler ebb and flow of woman's sex has escaped man's observation or his care. ”
