For further information on this subject, I suggest you read Taking Charge of Your Fertility, by Toni Weschler.  Even if you are wearing a penis, like me. Luna Book  2003 paper, leather, brass.  6"x9" It is interesting how little we understand about our own bodies. This is especially so in the area of women's reproductive health, a taboo subject shrouded in superstition, misinformation, and occasionally even derision by most of the population. This workbook contains the necessary charts for a woman to track her natural rhythmic cycles and related physiology such as basal temperature,  vaginal secretions, and cervical position. The front plaque is a waxing moon, symbolic of both the relationship between lunar and female cycles, and also the growing soverignty of women over their own bodies, a soverignty without chemicals, devices, and manufactured hormones.  The clasp and back knotwork are stylized spermatozoa, to complete the equation-  without man there can be no woman; and without woman, there can be no man.