For more than 150 years, historians have speculated about what made Abraham Lincoln great. Some point to Lincoln's study of grammar, literature, and poetry. Others believe it was the deep national crisis that elevated Lincoln's oratory. Most agree though that he honed his persuasive technique in his work as an Illinois attorney. Authors Hirsch and Van Haften persuasively argue, for the first time, that it was Lincoln's in-depth study of geometry that gave our sixteenth president his verbal structure. Although Lincoln's fascination with geometry is well documented, most historians have concluded that his study of the subject was little more than mental calisthenics. In fact, conclude the authors, Lincoln embedded the ancient structure of geometric proof into the Gettysburg Address, the Cooper Union speech, the First and Second Inaugurals, his legal practice, and much of his substantive post-1853 communication. Modern science can be traced back to Greek geometric method, but rhetoric, which morphed into speech and then into communications, has barely advanced since Aristotle. Lincoln's structure emancipates speech from Aristotle and unleashes limitless possibilities. Indeed, his use of geometric method in rhetoric and writing has long been a secret hiding in plain sight. Virtually any literate person can become an Abraham Lincoln by structuring speech with iron logic, as aptly demonstrated by this remarkable new study. Among other things, the authors artfully demonstrate the real importance of the Cooper Union speech (which helped make Lincoln president), offer a startling revelation about the Declaration of Independence that connects Lincoln to Thomas Jefferson more closely than anyone previously realized, and show how the structure of the legal system played an even more important role in Lincoln's greatness than heretofore realized. With the paperback release of Abraham Lincoln and the Structure of Reason, Lincoln immediately takes on a new importance that will open an entirely new avenue of scholarly study.