Diana, Hecate, and Isis, and is often depicted as the Maiden, Mother, and Crone triad popularized by Robert Graves (see Triple Goddess below). Many depictions of her also draw strongly on Celtic goddesses. Some Wiccans believe there are many goddesses, and in some forms of Wicca, notably Dianic Wicca, the Goddess alone is worshipped. Some, but not all, participants in the Goddess movement self-identify as witches or Wiccans. Other participants of the Goddess movement call themselves goddessians while others identify as the more generic "pagans". Some witches, especially Dianics, attempt to trace the historical origins of their beliefs to Neolithic pre-Christian cultures, seeing Wiccanism as a distillation of a religion found at the beginning of most, if not all, cultures. They regard wise women and midwives as the first witches. Dianic witchcraft first became visible in the 1970s, alongside the writings of Zsuzsanna Budapest. Her feminist interpretation of witchcraft followed a few decades after the founding of Wicca by Gerald Gardner in the 1940s. Today, there are at least 800,000 individuals who consider themselves Wiccan followers or witches in North America. Gardner and Valiente advocated a proto-feminist ideal of priestess authority in service to the Wiccan God and Goddess. Covens in "traditional" Wicca (i.e., those run along the lines described by Gardner and Valiente) had and have pretty much equal leadership both of a priest and of a priestess; but often consider the priestess "prima inter pares" (first among equals) - according to the book A Witches' Bible, by Stewart and Janet Farrar. Doreen Valiente became known in Britain as the 'Mother of the Craft' and contributed extensively to Wicca's written tradition. She is the author of The Witches' Creed, which lays out the basics of Wiccan religious belief and philosophy; including the polarity of the God and the Goddess as the two great "powers of Nature" and the two "mystical pillars" of the religion. One way to characterize the central male-female divine dyad in Wicca is to say that it's a duotheistic religion with a theology based on the divine gender polarity of male and female. The existence of witchcraft as the remnants of an old pagan religion as late as the early Modern Age was first suggested to a wide readership by Margaret Murray's books, The Witch-Cult in Western Europe, The God of the Witches (1933) and The Divine King in England. Her works have since been largely