Deep in her new book, “Oath and Honor,” Liz Cheney points out that the likeness of Clio, the Greek muse of history, is found in the Capitol’s National Statuary Hall. “Clio is depicted riding in the chariot of time, making notes in the book in her hand,” Cheney writes, “as a reminder that what we do in the Capitol Building is written in the pages of history.”Cheney’s book is likewise an attempt to write the history of our time, a history in which Cheney has become a protagonist. Her telling of this history, though vital, is unnecessarily partial. If this book is intended as both “a memoir and a warning,” as its subtitle declares, Cheney delivers on only half of that promise.The warning Cheney issues is clear and persuasive: A second presidential term for Donald Trump would pose great risks to the nation’s democratic practices and identity. A retribution-minded, Constitution-terminating leader buttressed by unscrupulous advisers and ethically impaired lawyers could, she argues, “dismantle our republic.” As both a witness and a target of the Jan. 6 assault on the Capitol and as a leader of the House committee that investigated the attack, Cheney recognizes the power of the mob that Trump commands. She also understands the cowardice of his enablers in the Republican Party, the same kind of loyalists who would populate — or at least seek to justify — a second Trump administration.“The assumption that our institutions will protect themselves is purely wishful thinking by people who prefer to look the other way,” Cheney writes. And that was before Trump suggested that he would act dictatorially in his new term, if only on day one.As a memoir, however, Cheney’s book is overly narrow, and at times curiously uncurious. Yes, anyone interested in the author’s recollections from inside the House chamber on Jan. 6 will find plenty of material (when Jim Jordan of Ohio approached her to help “get the ladies” off the aisle, Cheney swatted his hand away, retorting, “Get away from me. You f — ing did this.”), and Cheney is unstinting in her contempt for Kevin McCarthy, then the Speaker of the House, whom she describes as unprincipled and unintelligent in roughly equal doses. (She even finds McCarthy less substantive and capable than Democratic leaders in the House, like Nancy Pelosi — a savage dig in G.O.P. world.)Yet, for all the insider detail Cheney offers, her memoir is truncated, treating the period between the 2020 election and the Jan. 6 attack as the beginning of history, or the only history that matters, as though no prior warnings about Trump had been warranted or even audible. Cheney once believed in the staying power of the country’s constitutional principles, she writes, “but all that had changed on January 6 of 2021.”Did nothing change for Cheney before Jan. 6? Not anything at all?Cheney, who has said elsewhere that she regrets voting for Trump in 2020, seems disinclined to revisit or reconsider in this book why she and so many others made their peace with earlier signs of Trump’s authoritarian, anti-constitutional impulses. Her explanation for voting against Trump’s first impeachment is thin; she wishes the Democrats had moved to subpoena John Bolton, Trump’s former national security adviser, to gather additional evidence. It’s a grudging excuse from Cheney, who, as a former State Department official, no doubt can recognize when diplomacy is being manipulated for domestic political gain.Instead, she merely decries those who failed to pivot away from Trump after the 2020 election and Jan. 6, blaming their social-media silos and their exposure to pro-Trump news outlets like Fox News and Newsmax. A longtime Wyoming donor, for example, had “fallen for all the nonsense” about election fraud, Cheney writes, while a close family friend “fell for the lies, hook, line, and sinker.”I did not expect “Oath and Honor” to double as a mea culpa; in any case, Cheney does not seem the type to dabble much in remorse. Her courage in challenging her party over Trump’s election fantasies is hardly rendered meaningless by her prior support for Trump, and her leadership of the House Jan. 6 committee elevated patriotism over partisanship. But history did not in fact begin with that day of violence at the Capitol nearly three years ago. Trump’s unceasing deceit, his disdain for the norms of his office and his assault on the institutions of government spanned his presidency, not just its closing weeks. And his declarations of supposed electoral fraud against him far predated the 2020 presidential contest; his similar rants ahead of the 2016 election were rendered moot only by his unlikely victory.Whether they are elected officials, media personalities, lawyers, family friends or the mob itself, people don’t just swallow Trump’s lies hook, line and sinker all of a sudden. They are lured in, one speech, one deception, one promise at a time, until a lie becomes a worldview. The most serious Trump enablers may indeed include elected officials like McCarthy and his successor Mike Johnson, both of whom brazenly supported Trump’s attempt to undo the 2020 election, and who come in for serious grief in Cheney’s book. But they are not the only ones who, at key moments throughout the Trump presidency, preferred to look the other way. Even those former supporters turned vocal opponents owe some explanation of why their minds needed changing — if only because their transformation can help illuminate the mindset of those who decline to follow their lead.It is largely correct to write, as Cheney does, that “no amount of evidence would ever convince a certain segment of the Republican Party.” It is also largely unhelpful.The irony of the history Cheney highlights in “Oath and Honor” is that her focus on the final days of Trump’s term in late 2020 and early 2021 proves quite helpful in anticipating what the early days of a second term might bring. Most of those troublesome “adults in the room” from the first Trump administration will be gone, consigned to the green room instead of the Cabinet Room. No one will threaten to resign citing principles for the simple reason that they won’t have any; loyalty will be their chief qualification.Cheney recalls how Ronald Reagan described America’s orderly transfer of power every four years as “nothing less than a miracle,” and she worries of the dangers that loom when that transfer grows disorderly. The transition from an outgoing administration to an incoming one is “a time of heightened potential vulnerability” for the country, Cheney writes, and she notes how, immediately after the 2020 election, Trump subbed out key senior officials — including the defense secretary — in favor of more pliable replacements. “Why was he appointing inexperienced loyalists to the most senior civilian positions in the Pentagon at a moment when stability was key?” Cheney asks. (After her service on the Jan. 6 committee, Cheney is able to answer her own question, concluding that Trump was considering “deploying our military for some election-related purpose.”) The president also tried to replace the attorney general with someone willing to falsely assert in writing that the 2020 vote was corrupt; only when multiple senior Justice Department officials threatened to resign did Trump back down.Now imagine an administration staffed that way from the beginning, starting on Jan. 20, 2025, and buttressed by empowered collaborators in Congress, and you’ll grasp Cheney’s most serious warning. “I am very sad to say,” she acknowledges in her final pages, “that America can no longer count on a body of elected Republicans to protect our republic.” It’s a remarkable statement considering the political lineage of its author, but a defensible one. Just as the history Liz Cheney tells in “Oath and Honor” should go back further than the lies about 2020 and the scandal of Jan. 6, the damage of a second Trump term would extend far beyond whatever measures he might inflict on day one.The Times is committed to publishing a diversity of letters to the editor. We’d like to hear what you think about this or any of our articles. Here are some tips. And here’s our email: letters@nytimes.com.Follow the New York Times Opinion section on Facebook, Instagram, TikTok, X and Threads. More