Books like the women's encyclopedia of myths and secrets

Metaformic Theorystates that modern-day material culture is rooted in ancient menstruation rituals, called "metaforms". Metaforms are rituals, rites, myths, ideas, or stories created to contain emerging knowledge relating to menstruation.

Metaformic Theory is founded upon anthropological data and artifacts used in menstruation rites or rituals recorded over the last 400 years. The most common of these are menstrual seclusion rites. Menstrual seclusion rites incorporated three basic restrictions for menstruating women: they must not see light, touch water, or touch the earth. Metaformic theorist, Judy Grahn uses the theory to examine how these restrictions "constructed our minds externally, not abstractly, but through using physical metaphors—metaforms—that embody a comparison to a menstrually based idea."