He was born two months prematurely, so underweight and unattractive that his own mother said, "When I saw him I could see no promise in him." As a boy, he was an uneasy soul who walked in his sleep, a poor student who daydreamed rather than studied until he dropped out of school at the age of 12.
When he became a man - and later a celebrity - he was still wild and disreputable, so much so that when he asked his friends (and these were his friends, mind you) to recommend him to his fiancée's parents, most suggested they grab their daughter and run.
Yet he was also a man of immense sensitivity, whose youthful feelings and impressions both haunted and sustained him throughout his lifetime. He became an adoring husband and so tender a father that when his eldest daughter went to college he longed to deliver her laundry just so he could be near her. All his passions were larger than life and they shaped his story, for good and for ill.
But most important, he is the man many credit with giving American literature its voice. He is Mark Twain, and thanks to Ron Powers we now have a new biography, Mark Twain: A Life, carefully crafted to help us experience the restless, complex, enormously gifted Samuel Clemens as a living, breathing, three-dimensional being.
Powers has written extensively about Twain in the past (including an earlier book called "Dangerous Water: A Biography of the Boy Who Became Mark Twain.") His gift here, however, is, first, to deliver the writer to us with subtlety and sensitivity, and then to set Twain's life story in the context of the growth of the United States, which was still an infant country full of potential but raw, rough, and unformed in 1835 when Samuel Clemens was born.
Sammy, as he was first known, came to a family that seemed destined to struggle. His father, although a bright and self-educated man, wasted his time and energy on a series of failed business schemes. (It was a pattern to be repeated throughout the lives of Twain's older brother Orion and even Twain himself.)
But despite the family's economic struggles, Twain's boyhood gave him material to feed on for the rest of his days.
He spent his formative years in Hannibal on the banks of the Mississippi and in slave quarters where a slave named Uncle Dan'l (a model for Jim in "Huck Finn") told stories and delighted the young boy with his language and rhetorical skills.
Young Sam, however, never stood still for long - not at any stage of his life.
By the time he was 18 he had already traveled more than 2,000 miles, lived in three major East Coast cities, and worked as a newspaper correspondent.
During the next decade he would make 120 steamship trips on the Mississippi, enjoy a wild interlude in Nevada and California (in part to avoid fighting in the Civil War), travel abroad, gain a national reputation as a humorist, and become almost an overnight sensation as a lecturer.
Twain channeled the adventures of his rough-and-tumble life into new institutions springing up in America. He began writing for newspapers just at a time when they traveled far and wide enough to win a gifted local writer a national audience. He was - literally - pushed onto the lecture stage when Americans flocked to such entertainment. And he moved into book publishing just as a growing US middle class made the industry viable.
Twain's remarkable wit certainly established his enormous early celebrity (Powers calls him the first rock star), but his enduring appeal is far more complex.
His is an original voice - and as Powers points out - a uniquely American voice. He brought the freshness and authenticity of Western language to readers on the East Coast and in Europe, and he shattered the sweet sentimentality of the literature of his time, replacing it with realism, with what James Agee would later call, "The Cruel Radiance of What Is."
In 1885 he gave the world "The Adventures of Huckleberry Finn," the novel from which, Ernest Hemingway once said, "all modern American literature comes." It was also the book - for all the racial controversy that it still creates - that brought African-American voices straight into the heart of US literature.
Powers does a thorough job of tracking Twain's development both as a writer and a human being, and the book offers some particularly lovely pleasures, including the treatment of Twain's great love for his wife (one of the funniest men in America, he chose to marry a sweet, earnest intellectual slow to grasp his jokes, whom he called his "dear little concentration of Literalness"); his long friendship with fellow literary giant William Dean Howells; and the description of the black child who served Twain dinner one night and helped to unlock the voice of Huckleberry Finn.
For the general reader, there are places where Powers's detail may grow tiresome and slow the energy of the narrative. But there are few quarrels to be made with the quality of his research (although the book does contain a completely inaccurate definition of Christian Science, offered in passing as Powers details some of Twain's tirades against Mary Baker Eddy, founder of this newspaper.)
The book's ending is bleak. Twain's vision was always dark, but his latter years were truly tragic, including the loss of his wife and two of his adult children.
Writing about a man vastly uncomfortable with sentiment, Powers manages to deliver Twain as an emotional being.
It's no small achievement. As Howells once remarked of his sharp-eyed but guarded friend, "You were all there for him, but he was not all there for you."
• Marjorie Kehe is the Monitor's Book editor.