It seems that writing a query letter is an art unto itself. Some of the advice I found applied more to novels or to narrative non-fiction than to a historical and philosophical inquiry into religion, but the basic idea of describing your work in a few tight paragraphs, starting off with a one or two sentence "hook", seems pretty sound.
So here's what I came up with. I know in trying to explain this darn thing to some of you before, I've ended up going off on tangents or tripping over my tongue -- hopefully this is clearer! I will be continuing to polish both it and the manuscript itself.
Shortly before his death, John Lennon called himself a "Zen Pagan." With this he gave an excellent name to a religious trend that goes back at least as far as Henry David Thoreau, who wrote of his love and respect for both the ancient nature god Pan and the Buddha.
The connection between Buddhism and nature spirituality is ancient. According to legends of the Buddha's enlightenment, in his hour of need he asked the Earth to bear him witness, rather than appealing to a heavenly deity. Over the centuries Buddhism influenced and was influenced by nature religions like Taoism and Shintō, and its introduction to the West came partly by the work of spiritual nature writers like Thoreau and Gary Snyder. Occultists like Aleister Crowley and H.P. Blavatsky played key roles in both Buddhist and Pagan history.
Why Buddha Touched the Earth: Zen Paganism for the 21st Century investigates these connections. It combines rigorous historical research with lively and practical discussions of mysticism, magic, meditation, ethics, and the future of religion.