“Thomas Jefferson” by Jon Meacham (Random House, $35)

“Master of the Mountain” by Henry Wiencek (Farrar, Straus and Giroux, $28).

The title of Jon Meacham’s new book may be “Thomas Jefferson: The Art of Power,” but make no mistake: This is a full biographical treatment of perhaps the most charming and unknowable of the founders. Impeccably researched and footnoted, it’s a model of clarity and explanation.

Unlike its subject, “Thomas Jefferson” is not stylish. Meacham distills, and explains, and explains, and explains. And yet this kind of approach — methodical, one might say leisurely — may be ideal, because so much about Jefferson is necessarily speculative. Meacham again and again couches his sentences with constructions such as “The likely truth is that” and “It is also possible.”

The darker side of life at Monticello is the subject of Henry Wiencek’s new “Master of the Mountain: Thomas Jefferson and His Slaves.” Meacham candidly admits that Jefferson “was to embody the slave-owning interest” in all his major postings and into his old age, then moves on.

For Wiencek, Thomas Jefferson is all about slavery, its economics, its brutality, its tragedy. Which leads us to the biography-reader’s inevitable dilemma: What was the subject really like?

Meacham can imagine sitting down and enjoying a glass of claret with the brilliant Renaissance man familiar to us all. Wiencek finds Jefferson a much sadder case, a man seduced and corrupted by the dollars and cents of slavery.

To understand the third president in context, stick with Meacham.