In the endnote attached to the poem, Snyder describes the sequence as "a sort of sutra—an extended poetic, philosophic, and mythic narrative of the female Buddha Tara"—a claim which is not merely rhetorical but indicates a clear and concerted effort to present a religious perspective combining the organic and cyclical cosmology of Zen and Tantric Buddhism with modern ecology. He even extends the bounds of traditional Buddhist doctrine by incorporating the latest scientific advances, creating in the process his own idiosyncratic Goddess-oriented Buddhism opening onto a cosmological dimension.

In its explicit embrace of Buddhism, Mountains and Rivers returns to and reaffirms Snyder’s origins in the Beat Movement, the San Francisco Poetry Renaissance, and the curious religious revival movement of American Buddhism. The Beats, as is well known, rebelled against the conformity of the Eisenhower Era and extolled the life of liberty on the open road amid the vast open spaces of the American West—a dream of footloose freedom forever immortalized in Jack Kerouac’s On the Road (1955). Their conscious decision to opt out of the "system" by adopting an alternative lifestyle was not just escapism—as has often been charged—but followed from an authentic spiritual quest and searching-out-of-the-truth. Through cultural transmitters such as D. T. Suzuki and Allan Watts, the Beats adapted Buddhism to the American vernacular. Practically all the Beats studied Buddhism as a religious option, but Snyder was the most consistent of the group, and Buddhism informs virtually his entire oeuvre.

Snyder foregrounds his participation in the Beatnik movement and the trans-Pacific flourishing of American Buddhism in many of the early poems of the Mountains and Rivers sequence. In a poem called "Night Highway 99," written in 1962 as part of the original Mountains and Rivers, Snyder gives an account of his travels up and down the Pacific Coast in the late fifties, tracing the spiritual cartography of the American highway at a time when it was still possible to hitchhike from Seattle to San Francisco with relative ease. "Night Highway" ends up in North Beach and recalls Snyder’s participation in the San Francisco Poetry Renaissance and such historical happenings as "The Human Be-In" in Golden Gate Park and the Ginsberg "Howl" event. We are reminded—if there was ever any doubt—that Snyder was a central figure of the West Coast branch of the Beat Movement, at the very epicenter of an exciting circle of creative activity, even something of a guru, renowned for his wisdom in matters of myth and mountaineering.

Another early poem, "The Circumambulation of Mt. Tamalpais," first published in 1966 in Coyote’s Journal, records an actual event: Snyder’s inauguration, along with Philip Whalen and Allen Ginsberg, of a pilgrim route around Mt. Tamalpais in the Asian "sacred mountain" tradition, complete with various invocations and mantras (Whalen and Ginsberg also recorded the event in their own poems). The poem plots an elaborate Buddhist liturgy, proving that ascending even humble Bay Mountain can become a meaningful spiritual experience, analogous to climbing the Buddhist and Taoist holy mountains in China and Japan. A contemporary poem, "Three Worlds, Three Realms, Six Roads" translates some of the more obscure concepts of Buddhist cosmology into a stylized account of Snyder’s own itinerant spiritual wanderings as he travels from Seattle to Portland to San Francisco, and finally on board a ship bound for Kyoto.

In "The Blue Sky," first published in 1968, Snyder pays tribute to the Pure Land sect of Buddhism and to the Tathagata Buddha of Healing, whom he brings into dialogue with the Medicine Man of Native American lore. Similarly, in the "Hump-Backed Flute Player," first published in Coyote’s Journal in 1971, Snyder draws parallels between Native American and Buddhist themes, searching for a common Shamanistic origin in the figure of the wandering flute-playing bard, whose petroglyph can be found in the Canyon de Chelley and whose heir is the modern backpacker. Reading Mountains and Rivers in the context of Snyder’s lifelong dedication to Buddhism and his own evolving idiosyncratic devotions helps to underscore the religious dimensions at the core of the poem, which I believe represents a final and mature effort (after such playful starts as the "Smoky the Bear Sutra") to write a sacred text for a new kind of ecologically-informed American Buddhism.

At the same time as Snyder was deepening his understanding of Buddhist literature and practice, he was studying ecology and related disciplines such as geology and plate tectonic theory. Although the concordance between Buddhism and ecology has now become something of a commonplace, owing to the writings of E. F. Schumacher, Fritjof Capra, Thich Nhat Hanh and others, Snyder was one of the first to actively promote the idea in his poetry and in his critical writings. Buddhism gave Snyder an alternative philosophical and non-theistic religious framework to the dualisms of the Judeo-Christian and the Western metaphysical traditions. Ecology provided him with the facts and a firm grounding in science which thankfully restrained him from the excesses of the "disembodied" school of Beat poetry.

A voracious autodidact, Snyder made himself familiar early on with the advances in scientific ecology, from its initial academic successes in the fifties and sixties to later developments such as James Lovelock’s Gaia hypothesis down to the most recent studies in geomorphology. His grounding in science endows him with a Goethean ability to gaze across the "two cultures" divide between the sciences and the humanities which still splits our knowledge of nature into the "objective" categories of the natural sciences and the "subjective" apprehensions of poetry and the fine arts. For Snyder, as for Goethe, truth is one, and as Snyder’s work evolves in both its poetic and its critical dimensions, it strives towards a synthesis of the most up-to-date scientific understanding of nature with Buddhist cosmology, forming a complete worldview which honors both the scientist’s quest for objective truth and the poet’s search for meaning.

It is possible to identify at least three phases of Snyder’s involvement with ecology. The first goes back to the late fifties and sixties, when Eugene Odum’s model of organic holism was the dominant paradigm. Snyder, along with many others at the time, came to realize that ecology’s perspective of nature as the interplay of interconnected parts in which "everything is related to everything else" approximates the world-picture presented in Buddhist cosmology. The fruits of this engagement were published in Earth Household, a founding text of ecological radicalism, whose very title is a play on the Greek roots of the word ecology (from oikos meaning house or home, and logos meaning word or order). Its subtitle, "Technical Notes & Queries to Fellow Dharma Revolutionaries" gives some idea of its content and suggests how linked Snyder’s interest in ecology and in Buddhism were from the beginning. In this early period—consistent with the radical politics fashionable at the time—ecology became for Snyder the "scientific" justification for a revolutionary praxis in which the breakthrough into enlightenment is figured in political terms as a "flip" from current destructive and unsustainable practices to an adherence to the Dharma as it is revealed in nature. Snyder’s ecology, like his Buddhism, was from the beginning politically active, pointing down the path from right thinking to right action.

The second stage of Snyder’s engagement with ecology occurs after his return from Japan in the late sixties and his reading the work of James Lovelock and others. Lovelock’s Gaia hypothesis provided him with a model of the biosphere as a single self-regulating organism, which he then brings into relation with the Goddess archetype in both the Western and Eastern traditions (as in "Short Songs for Gaia" in Axe Handles). After settling down on his homestead in the Upper Yuba valley, Snyder became increasingly involved in watershed ecology, in the idea and practice of building sustainable communities, in the bioregional movement, and in multiple personal projects aimed at cultivating a healthier relationship with the land (most of this falls under the rubric of what he calls "reinhabitation," by which he means learning to live on the land as biologically naturalized citizens). In addition, his thinking during this time is influenced by the traditions of Buddhist philosophy and cosmology, and chiefly by Dogen, whose vision of a living universe in which "the blue mountains are constantly walking" provided him with a model for a process cosmology enriched by many points of contact with modern ecological theory. This second period of Snyder’s engagement with ecology is represented most explicitly in Turtle Island (1974), which presents a vision of a new America premised on the imperative of reinhabition.

The third stage of Snyder’s synthesis of Buddhism and ecology belongs properly to the final period of the Mountains and Rivers project, coming in a flurry of inspiration in the mid-nineties and connected with the final push to complete the poem. Whereas the earlier poetry dwelt mainly at the level of immediate sensory experience of nature, the later poetry penetrates deeper into the inner workings of natural processes, concerned not so much with topical impressions as with larger earth-shaking events such as subduction, uplifting, and the clash of continental plates. In these later poems Snyder offers us a vision of the Earth as a single creative process evolving along a space-time continuum. Especially evident in these later poems is a deeper understanding of the cosmic story, of the epistemological implications of evolutionary theory, and a highly technical grasp of the morphological processes which are still shaping the living tissue of the planet. His achievement in these later poems is to fashion a kind of interactive scientific-poetic discourse in the tradition of Lucretius, Erasmus Darwin, and Goethe, which celebrates the creativity of the Earth with the precision of scientific observation but expressed in the co-creative activity of the poetic imagination.

These later poems, in the fourth and final section of the Mountains and Rivers sequence, represent a deepening of Snyder’s overall poetic vision and a substantially new contribution to American nature poetry. The poem entitled "The Mountain Spirit," a dream-vision loosely modeled on the archaic No play Yamamba (Old Mountain Woman) may be taken as the visionary epicenter of the entire set and Snyder’s most consummate effort to date to arrive at a synthesis of Buddhist cosmology with an up-to-date ecological understanding of natural processes.

The Mountain Spirit is a goddess figure: Mother Nature, Gaia, the Ewige Weibliche known by many names. For an ecological poet like Snyder, she is mistress and muse, the voice of nature with whom he can enter into creative dialogue. Snyder uses the conventions of the No literary form, steeped in archaic Shinto tradition and infused with an earlier animism, to serve as a vehicle for his vision of a living and evolving universe. The poem opens with an incantatory repetition in the Eastern fashion, almost like a Buddhist chant, affirming the analogy between geological cycles and the cycles of mortality:

After the opening mantra, the poem moves from the lofty terrain of metaphysical speculation to the rough and real terrain of the Western American landscape, while at the same time transposing the form of the No drama into a distinctively American idiom. The poem is structured as an initiation of sorts in which the reader finds himself with Snyder on an overnight vision-quest. The object of the poet’s quest is the fabled Bristlecone Pine. These trees, which live on the edges of the Great Basin, grow in twisted and gnarled fashion with new wood constantly coiling around the old, and are among the oldest living beings. Bristlecone appears frequently in Snyder’s work as a symbol of nature’s longevity, and of a time frame which stretches back beyond recorded human history. In this poem, the Bristlecone Pine serves as a symbolic center around which the poet and the Mountain Spirit, his lover and friend, can enter into a kind of sacred communion. The vision proper begins later that night under a precise astrological coincidence, when Mirfac, "the brilliant star of Perseus," crosses over the ridge at midnight. We find the poet in a kind of trance, Manfred-like, staring out over the vast abyss, inspired by the breezes coming up from the flatlands below and by the shooting stars above. There he has a vision of ever-creative nature, of the whole universe literally palpitating with life, and there he begins the recitation of the poem of all poems, the poem of the earth:

What Snyder presents here is not just dreamy nature poetry, but a poetry of nature informed by a precise, up-to-date scientific understanding of the geophysical processes which are still shaping the earth’s crust. The "ice-carved cirques," for instance, refers to the repeated cycles of glaciation as rivers of ice moved up and down the valley during the Pleistocene (a theory, incidentally, first adduced by John Muir to explain the polishing of the steep cirques in Yosemite). Words like "dendritic" and "fractal," lifted from the geologist’s lexicon, enter into the service of poetry in an effective concatenation of unlikely sounds and images. The admixture of geological insight with a poetic ear allows Snyder to come up with such felicitous phrases as "calcium-spiraling shells," "magma-swollen uplands," "ranges into rubble" and "lime-rich wave-wash soothing shales and silts." Or he can celebrate a single tectonic event:

The sudden disappearance of the Mountain Spirit—"and then she’s gone"—does not, however, leave the poet exactly forlorn. Just when the poem seems to drift off into some sort of hopelessly Romantic Sehnsucht, Snyder reaffirms his craft by ironically wrapping up his nocturnal vision with a matter-of-fact and even humorous closure. Posing as if tired of bantering with spirits and wishing for sleep, he bids goodnight to both his dancing partner and his reader and returns to his bivisack spread out under the open sky: "A few more shooting stars/ back to the bedroll, sleep till dawn."