Robert DOUGLAS-FAIRHURST, the Oxford scholar who is one of Charles Dickens’s two new biographers, rightly calls his subject “at once the most central and most eccentric literary figure” of his age, and the investigations into the dark corners of that eccentric life began with Dickens himself. In 1849 he showed a short account of his early years to his close friend John Forster, revealing a story he never told his own family: the shame-inducing months he spent, while his father was in a debtor’s prison, as a 12-year-old “laboring hind” in a factory that bottled shoe-blacking. The first volume of the biography he’d wanted Forster to write — which made the ­blacking-factory episode public — appeared in 1872, two years after Dickens died at the age of 58, and its successors keep coming. The Dickens biographies published just in the past 25 years make an impressive stack. Given his uncanny genius and the vivid complexity of his life, that’s not a complaint.

Still, in all these books, the most memorable moments come from the accounts of those who saw him in person. I’d trade a whole pile of biographies for a video clip of the young Dickens, while courting Catherine Hogarth, his wife-to-be, leaping unannounced through the French windows of her family’s house in a sailor suit, dancing a hornpipe, leaping out again, then walking in at the door “as sedately as though quite innocent of the prank.” And I’d trade that clip, plus the biographies, for footage of Dickens’s face-to-face interview with his admirer Fyodor Dostoyevsky in 1862. “He told me,” Dostoyevsky recalled in a letter written years later, “that all the good, simple people in his novels . . . are what he wanted to have been, and his villains were what he was (or rather, what he found in himself), his cruelty, his attacks of causeless enmity towards those who were helpless and looked to him for comfort, his shrinking from those whom he ought to love. . . . There were two people in him, he told me: one who feels as he ought to feel and one who feels the opposite. From the one who feels the opposite I make my evil characters, from the one who feels as a man ought to feel, I try to live my life.”

Claire Tomalin, the other new biographer, who quotes this confession in “Charles Dickens: A Life,” calls it “amazing” — though it’s only amazing because it’s the image-conscious Dickens himself coming out and saying what anybody familiar with his work and his life has always intuited. “It is as though with Dostoyevsky he could drop the appearance of perfect virtue he felt he had to keep up before the English public.”

As Tomalin notes, this “must be Dickens’s most profound statement about his inner life,” and it seems to be one of the few crucial bits of Dickensiana that’s relatively fresh. Both Tomalin and Michael Slater, who cites the same passage in his 2009 biography, “Charles Dickens,” found the newly translated Dostoyevsky letter in a 2002 article in The Dickensian. Neither Fred Kaplan (“Dickens: A Biography,” 1988) nor Peter Ackroyd (“Dickens,” 1991) seems to have known about it. Mostly, the recent biographies are remixes of familiar episodes and anecdotes; their interest lies largely in what’s included and what’s left out, how deeply the biographer goes into unpublished or unfamiliar work, and what’s adduced from further research into the world in which Dickens lived and worked.