Michael Stillwater is the founder of Inner Harmony. With his partner, Doris Laesser, he led a group of Americans on a dark retreat in Switzerland in January 2006. He lives in Marin County, Calif.

Mirabai Starr is an adjunct professor of religious studies and philosophy at the University of New Mexico in Taos. She is the translator of St. John of the Cross’ Dark Night of the Soul (Riverhead, 2002).

Joan Halifax is the author of Fruitful Darkness: A Journey Through Buddhist Practice and Tribal Wisdom (Grove Press, 2004). She is the founder of Upaya Zen Center in Santa Fe, N.M.

Martin Lowenthal is the founder and director of the Dedicated Life Institute in Newton, Mass. He is also the author of Dawning of Clear Light: A Western Approach to Tibetan Dark Retreat (Hampton Roads, 2003).

Rabbi Ephraim Buchwald is founder of the National Jewish Outreach Program, which tries to keep Jews engaged in Jewish life, particularly when the cause was assimilation or lack of Jewish knowledge. It sponsors the annual Shabbat Across America program.

Thomas Cahill, an Irish Catholic, is author of How the Irish Saved Civilization (Anchor, 1996) and served for a time as the North American education correspondent for the Times of London.

John P. Gluck is a professor emeritus of psychology at the University of New Mexico, Albuquerque. Originally a comparative psychologist specializing in learning ability of nonhuman primates, he now studies the ethical justification of animal research.

Laura Hobgood-Oster is a professor of religion at Southwestern University in Georgetown, Texas. Her areas of expertise include animals in the history of the Christian tradition and contemporary religious-ethical issues related to other-than-human animals. She is the author of Holy Dogs and Asses: Animals in the Christian Tradition (2008).

Carol J. Adams is an independent scholar and self described “feminist-vegan” based in Dallas, Texas. She writes and lectures widely. She has written about the relationships between religion and animals.