Rich married and bore three children before the age of 30. Motherhood radicalized her. “I began at this point to feel that politics was not something ‘out there’ but something ‘in here’ and of the essence of my condition.” She became troubled by the ways she “suppressed, omitted, falsified even, certain disturbing elements, to gain that perfection of order” in her early work. The next book, “Snapshots of a Daughter-in-Law” — “jotted in fragments during children’s naps, brief hours in a library, or at 3 a.m. after rising with a wakeful child” — was a departure in style and subject, written with free meter and bared teeth.

Rich left her husband and flung herself into antiwar and antiracist activism. She began a lifelong relationship with the Jamaican-born novelist and poet Michelle Cliff. In her transformation, some saw the evolution of American women in the 20th century: “from careful traditional obedience to cosmic awareness,” wrote the critic Ruth Whitman.

Others were less enchanted. “I don’t know what happened,” Elizabeth Hardwick tutted. “She got swept too far. She deliberately made herself ugly and wrote those extreme and ridiculous poems.”

This is the usual charge levied at Rich — that she was more polemicist than poet. These essays tell a different story. We see how frequently, and powerfully, she wrote from her divisions, the areas of her life where she felt vulnerable, conflicted and ashamed.

“I’m not able to do this yet.” “Nothing has trained me for this.” “I feel inadequate.” “My ignorance can be dangerous to me and to others.” All these sentiments appear in one paragraph of “Split at the Root.” But then, Rich gathers herself; she persists: “We can’t wait to speak until we are perfectly clear and righteous. There is no purity and, in our lifetimes, no end to this process.” For her, a thinking life, a political commitment, does not mean achieving perfect awareness — call it wokeness or whatever else — but embarking on “a long turbulence.” It is a perpetual “moving into accountability,” never an arrival. “By 1956, I had begun dating each of my poems by year. I did this because I was finished with the idea of a poem as a single, encapsulated event,” she wrote. “I knew my life was changing, my work was changing, and I needed to indicate to readers my sense of being engaged in a long, continuing process.”

These essays are as close as we will get to Rich for the time being. Many of her letters are sealed until 2050, and she left instructions to family and friends not to cooperate with any full-length biographies.

It’s not intimacy that these pieces afford; as much as Rich tells us, there is more that she conceals, especially about her private life — the apparent suicide of her husband, the years with Cliff. But it is a peerless pleasure to join her in the “long turbulence,” to think alongside her. I once read that a blue whale’s arteries are so large that an adult human could swim through them. That’s what entering these essays feels like — to flow along with the pulses of Rich’s intelligence, to be enveloped by her capacious heart and mind.