Famed for his dictionary, “Rambler” essays and The Lives of the English Poets, Samuel Johnson (1709–1784) remains one of the most-quoted and carefully observed authors who ever lived. On the occasion of Johnson’s tercentenary, Martin (A Life of James Boswell) searches out the psychological elements covered up by Boswell and others: the immense insecurities, bouts of deep depression, corrosive self-doubt and, in his last days, despair for his very soul. He grew up the illness-wracked, nearly blind son of a backwater bookseller. Martin shows how Johnson’s distant relationships with his family came to haunt him on the death of each member. Likewise, Johnson’s strange mannerisms and disfigurement, marriage to a woman twice his age and poverty early in his career further shaped his psyche. Through all this, Martin says, Johnson was also a bit of a ladies’ man, and notes in Johnson’s journal references to the practice or condition of “M.,” which, Martin speculates, stands for masturbation or defecation. Martin admirably succeeds in giving a new generation Dr. Johnson, warts and all, from the inside, though in prose that remains only serviceable. 30 b&w illus., map. (Sept.)