I wrote my undergraduate thesis on presidential disability and succession. This book was an invaluable resource, rich in detail, context, and analysis. Published in 1951, four years after the Presidential Succession Act of 1947 (which is still the law today), the book is a definitive source for how law and custom evolved throughout the nineteenth and first half of the twentieth centuries. As Professor Silva's introduction explains, her "approach is partly legal, partly historical, and partly analytical," and it is highly satisfying on all counts. The book covers nearly every nuance of applicable law and history, from well-known matters like the "Tyler precedent" (establishing the principle that, when a president dies in office, the vice-president becomes the president, not merely the acting president) to less-known anecdotes such as how President Arthur provided for his own incapacity when he succeeded the assassinated President Garfield and there was no vice-president, the Senate had not yet elected a president pro tem, and the House had not yet elected a speaker. When Congress was considering in the mid-1960s what ultimately became the Constitution's twenty-fifth amendment, almost every player in the debates relied on Professor Silva's work as a primary authority. No book since--not even John Feerick's excellent "From Failing Hands" and "The 25th Amendment"--has so thoroughly covered this critical but neglected subject.