Political insiders and many others have a treat this month: new biographies from the two greatest living practitioners of that form: Robert Caro (“The Passage of Power,” his continuing story about Lyndon Johnson) and David Maraniss (“Barack Obama: The Story”).

I have read all of their books, with the exception of the back half of Maraniss’s “Rome,” which I left on a plane but intend to finish.

All these books made a lasting impression, and I recommend them highly. What might the two men tell us about politics more generally?

In some ways the insights of their biographies are generally quite different. In real estate titan Robert Moses and Lyndon Johnson, Caro saw stories of how power can be used for great good but how it also can corrupt. In Bill Clinton, and now Barack Obama, Maraniss’s insights are much more personal and psychological about his subjects.

It may be an obvious but interesting distinction based on the times their subjects lived. It’s doubtful we will ever again see power wielded on a scale that built New York’s key infrastructure in just a couple of decades (Moses) or that passed the Great Society programs (Johnson). Caro, like his subjects, is firmly rooted in the 20th century of American hegemony.

Maraniss, who is a Post associate editor, is a child of the ’60s, and his subjects carry that era's legacy of doubt. In our times, nothing is pure text: Sub-text is often all. No one is better than Maraniss in finding the truth buried under all the artifice of modern politics.

What remains a constant throughout both authors' works: the ambition of their subjects. Moses and Johnson not only achieved great power but did great — and awful — things with it. Clinton and Obama achieved power but were unable to wield it in quite the same way.