'Debt takes its Toll.' Thus does Amity Shlaes begin her biography of Calvin Coolidge, the laconic, flinty-faced New Englander who became America's 30th president upon the death of Warren Harding in 1923 and then captured the office in his own right in 1924. Ms. Shlaes, the author of a best-selling history of the Great Depression, "The Forgotten Man" (2007), issues her debt admonition in the course of introducing Oliver Coolidge, a brother of Silent Cal's great-grandfather, who went to jail in 1849 because he couldn't pay a $29.48 debt to a neighbor. She then glides briskly from Oliver's plight to the problem of government debt, particularly when it reaches proportions that threaten the public fisc and undermine national confidence. "There have been times," Ms. Shlaes writes in the introduction to "Coolidge," "when debt pinned down the United States as it once pinned down Oliver.''
