By the time he’s done quoting, in blogospheric fashion, the wisdom of his earlier works (he cites “A Republic, Not an Empire,” “State of Emergency” and “Where the Right Went Wrong” in the first 33 pages alone), including articles in political journals like The American Conservative and The National Interest, “Day of Reckoning” has begun to feel like a cross between a greatest-hits anthology and “The Patrick J. Buchanan Reader.”