In her seminal essay on the 1960s, "The White Album," Joan Didion captures that tumultuous decade in a single declarative sentence: "So many encounters in those years were devoid of any logic save that of the dreamwork." A similar ineffability pervades "Upstream," a very different collection of selected essays from Pulitzer Prize-winning poet Mary Oliver, whose quiet woods and ponds on Cape Cod are as indelible as Didion's psychedelic California, attesting to a common faith in the yin and yang of dreams and consciousness, of forging one's path through the torque and tangle of the world.

For five decades Oliver lived in Provincetown, Mass., long before it became a bohemian haven and an LGBT mecca. A sense of elegy hovers over these essays, most of them less than 10 pages long, as Oliver mourns the passing of a fishing community into a tourist destination. Townspeople come and go, cheery visitors in her daily routine, and Oliver isn't averse to them, but she craves her solitude.

She seeks refuge in the forests that fringe the ocean, for her a kind of secular chapel, where she discovers the marvel of nature renewing itself, as in this scene of a turtle burrowing a nest for her eggs: "She sees me, and does not move. The eyes, though they throw small light, are deeply alive and watchful. If she had to die in this hour and for this enterprise, she would, without hesitation. She would slide from life into death, still with that pin of light in each uncordial eye, intense and as loyal to the pumping of breath as anything in this world."

This is no mere anthropomorphizing, but rather a deeper, quasi-religious connection to the natural world, a singular passion that shines in each paragraph. Oliver conflates it with her other great love, literature: "Upstream" includes essays on Emerson, Poe and her beloved Whitman, gems of criticism that surpass the dreary writing we often see in academic journals.

As with Emerson, Oliver's "I" is an eyeball of acute observation and insight, bridging her outer and inner landscapes with diamond-cut prose that only a poet could write: "This is where, once, I heard suddenly a powerful beating of wings, a feisty rhythm, a pomp of sound, within it a thrust then a slight uptake. The wings of angels might sound so, who are after all not mild but militant, and cross the skies on important missions. Then, just above the trees, their feet trailing and their eyes blazing, two swans flew by."

Oliver immerses us in an ever-widening circle, in which a shrub or flower opens onto the cosmos, revealing our meager, masterful place in it.

"Upstream: Selected Essays," by Mary Oliver

Hold "Upstream" in your hands, and you hold a miracle of ravishing imagery and startling revelation.

Hamilton Cain is the author of "This Boy's Faith: Notes From a Southern Baptist Upbringing." He lives in Brooklyn.

Upstream
By: Mary Oliver.
Publisher: Penguin Press, 175 pages, $26.