That is Professor of Political Philosophy (Emeritus), Harry Jaffa, in his recent book, A New Birth of Freedom: Abraham Lincoln and the Coming of the Civil War (2000).
"A New Birth of Freedom is a master work by a true and learned master of history and philosophy. It is a must for every serious student of the founding of our nation, of Abraham Lincoln, and of the Civil War." - The Civil War News
"With A New Birth of Freedom Harry V. Jaffa reestablishes himself as the greatest living scholar of Lincoln's political thought and Lincoln's greatest defender, period. For every citizen interested in the preservation of the American union and the principles on which it rests, Jaffa's book is a must-read." - Steven B. Smith, Yale University
"No mere review can do justice to this new book; suffice to say that it as a stunning work of scholarship and erudition that vindicates Lincoln against both his contemporary adversaries and those who in our own time would diminish him and the principles of the American Founding he sought to perpetuate." - The Washington Times
"A New Birth of Freedom more than meets the critical expectations that Professor Jaffa has invited in the years since his acclaimed study, Crisis of the House Divided .... A work of profound historical erudition and disciplined philosophical criticism, Jaffa's new work offers and original analysis of the crisis of the Union in the perspective of the Western political tradition and in the context of the constitutional principles of the American Revolution." - Herman Belz, University of Maryland, College park
Or so it is alleged. It still remains though that his only credential in any specific field that we know of is English, and yes - he did indeed used to teach literature.
"A New Birth of Freedom is a master work by a true and learned master of history and philosophy. It is a must for every serious student of the founding of our nation, of Abraham Lincoln, and of the Civil War." - The Civil War News
Anybody can dig up a favorable quote or two on virtually any book ever written - even crappy ones. Hell, try opening the movie section of your newspaper tomorrow and you'll find the exact same thing happens there. Every single ad for every single movie has some quote from somebody giving it a "thumbs up" or 4 stars or some other lauditory praise even if it's the worst movie of the summer and tanked at the box office. Same holds for books, and the fact remains that Jaffa's latest book bombed.