It is abundantly clear, nearly ten years since he descended that gold-trimmed escalator, that Donald Trump is the most significant political figure of our time. Even his most bitter enemies would have to admit, however distasteful it may be, that no president has held greater sway over American government other than perhaps Franklin D. Roosevelt during his 12-year presidency, and no single biography has displayed more variety, or taken as many improbable turns, since the rise of Theodore Roosevelt.