Lady Spender, Stephen Spender’s widow, once proposed in the Times Literary Supplement various draconian laws that should be applied to biographers,whom she thought of as appropriating their subjects’ lives. In the end, her legislative list would have made the practice of biography itself impossible – not such a bad thing, she probably thought. As an advocate for the other side, however, I propose a biographer’s defense act, which would allow biographers, once and for all, actually to tell readers how they acquire their material and what obstacles they encountered without having to suffer abuse from their sources.

Biographers do sometimes tell the truth about source acquisition and maintenance,but their confessions usually appear in obscure collections of criticism and in conference proceedings years after their books have been published. The actual acknowledgments sections of biographies seldom level with readers. Max Egremont’s preface to “Siegfried Sassoon: A Life” (Farrar, Straus & Giroux, 656 pages, $35) set me off on this line of thinking:

Sassoon’s importance, both literary and historical (rare in a writer), has led to many people going in search of him; since his death in 1967, there have been at least five full-length studies of his life and his work. So why add to an already crowded field? My answer is that, through Siegfried’s son George – who has never cooperated so extensively with a biographer before – I have been shown much new material. The substance of this is the unpublished manuscript diaries from 1926 onwards, Sassoon’s extensive notes for his autobiographies; and other correspondence and drafts of poems and prose books.

A little further on, Mr. Egremont adds, “When George Sassoon asked me to write this book, he also offered me his own memories.” Even better, George’s family, including his wife, Alison, pitched in to such an extent that Mr. Egremont concludes that his book “would have little point without it [their cooperation].” As if to apotheosize this symbiosis between biographer and subject, Mr. Egremont dedicates his book “For George and Alison.”

If this were a novel, the reader’s first question would be: How did the narrator come by his privileged information? The next: How reliable is he? Mr. Egremont claims an intimacy with his mate rial that other narrators (those previous five biographers) have not enjoyed.

That Mr. Egremont does not divulge more about the history of himself and the Sassoons disturbs but does not surprise me. The odd thing about biographers is that on the one hand, they divulge secrets (those delicious diaries!), and on the other hand, they shield the sources they depend on. Whatever the nature of the relationship between Mr. Egremont and the Sassoons may be – and I am not privy to inside information – I will bet you that it is of the greenhouse variety: carefully cultivated through elaborate venting, heating, cooling, and special light-filtering mechanisms the biographer has perfected in order to grow his story.

I cannot blame biographers for their tactfulness. I know from personal experience that to be utterly frank is to court withdrawal of affection and access. I can’t tell you how many times a biographer who has fulsomely thanked his subject’s friends and family in his acknowledgement has told me, in confidence, what a burden these sources have been. Indeed, one biographer I recently reviewed e-mailed me to say her biography had been held up for two years because of the family’s interference in her work. No mention of that problem in the book!

If Mr. Egremont has exercised my thinking on the biographer’s self-preserving sense of discretion, it is because he is unusually reserved. He does not even say if the Sassoons vetted his biography, or if they had any sort of veto on his narrative. Indeed, his dedication implies there is virtually no distance between the biographer and the subject’s family. I find that implication very hard to believe, given the expectations that arise when a biographer is allowed right of entry. He is, in effect, one of the family – until he writes the book – then comes the estrangement.

What sharpens my suspicion, I must say, is that there is already quite a comprehensive and recent competitor, Jean Moorcroft Wilson’s two-volume, “Siegfried Sassoon: The Making of a War Poet: A Biography (1886-1918)” (1998) and “Siegfried Sassoon: The Journey From the Trenches: A Biography (1918-1967)” (2003), which has just been reissued in a Routledge paperback.

Ms. Wilson, a lecturer in English at London University, has published biographies of Sassoon’s fellow war poets Isaac Rosenberg and Charles Hamilton Sorley. In the Scotsman, Robert Nye hailed her Sassoon as “the definitive biography,” and the Routledge paperbacks are studded with similar accolades. Of course, I scoured her acknowledgments, which begin with her tribute to George Sassoon, “who encouraged me to write this life of his father and allowed me to quote from his work.”

Indeed, Ms. Wilson quotes rather more from Sassoon’s published poetry than Mr. Egremont does. To my taste, the latter does too much snipping of Sassoon’s lines. Sassoon’s poetry is broken down into short phrases that make his work seem less impressive and more like fodder for the biographer’s narrative.

What happened after Ms.Wilson’s biography appeared? Was George Sassoon unhappy about it? Why did Alison Sassoon speak to Mr. Egremont but not to Ms.Wilson? Why did George Sassoon hold back certain of his father’s diaries for Mr. Egremont’s use? And how do those diaries and drafts alter our view of Sassoon?

Well, Mr. Egremont can fully document the development of the poet as never before. Siegfried Sassoon is one of the great poets of World War I. He captured both the lyrical side of men who believed that war could ennoble them, and the bitter, cynical, and satirical side of the same men who had to cross “no man’s land”- that indeterminate and harrowing space between the German and Allied lines that became a metaphor for what many soldiers and civilians alike came to see as the meaninglessness of war.

Sassoon is a great historical and literary figure of World War I because he was both pro- and anti-war. He had an almost foolhardy courage – “Mad Jack,” they called him – and once ran directly into enemy fire carrying a rope to drag a fellow soldier out of a 25-foot pit in the middle of no man’s land (the man died by the time Sassoon could get him back to Allied lines). Once wounded, however, he fell under the influence of Bertrand Russell’s pacifism (he met Russell and read his book “Justice in War-Time”). In 1918 he made a public statement announcing he would not return to the front and that the Allies had switched war aims from a defense of their land to an aggressive, imperialistic campaign.

Ms. Wilson calls his volte-face “impulsive.” Mr. Egremont deems it “naive” and misinformed. Sassoon himself thought better of his anti-war stance and did return to the front. Much later he explicitly repudiated his anti-war statement, although he remained rather closely allied with certain pacifists.

Mr. Egremont has the edge over Ms. Wilson in being able to show in detail how Sassoon’s poetic psyche evolved. For example, in an early draft of the front-line poem “The Redeemer,” Sassoon’s closing lines reflect, as Mr. Egremont points out, a “Brooke-like sacrifice”: “But in my heart I knew what I had seen / The suffering spirit of a world washed clean.”The final printed version is much more “grimly realistic,” the biographer suggests: “And someone flung his burden in the muck / Mumbling: ‘O Christ Almighty, now I’m stuck!'”

Any English major worth his degree can tell you Sassoon must have been reading A.E. Housman (Mr. Egremont confirms that it is so), but I wish the biographer had not dashed on to other matters without noting that Sassoon’s Housman-like power resides in the simplest lines.The individual soldier stuck in the mud was, of course, a whole civilization caught in the swamp of trenchwarfare. Sassoon was there – on the front line of history. In two lines, he shows it all.

Mr. Egremont’s allusion to “Brookelike,” by the way, indicates something about the book. He has written a biography for English majors. Unless you know about Rupert Brooke, Thomas Hardy, Walter de la Mare, Robert Graves, Wilfred Owen, and a host of other literary and cultural worthies, this biography, like its acknowledgments, will seem a bit opaque. Sometimes Mr. Egremont does slow down long enough to provide the kind of potted plot summary or biographical sketch the general reader needs, but often he does not. In those cases, it’s best to return to Ms. Wilson’s more extensive narrative.

Mr. Egremont writes well and has much new to tell us, but I can’t help still wondering about what he has withheld.

crollyson@nysun.com