The book follows Washington from a difficult childhood (his father's early death would prefigure his own) to a marriage that brought him great privilege and responsibility. "He came of age, and learned to be a master, on a racial borderland where the definitions and boundaries of race were dangerously fluid," Mr. Wiencek writes. This book offers many glimpses into the ways in which intertwined black and white family histories revealed the monstrousness of slavery-sustaining laws.

By nature, Washington was sufficiently prim to have copied out a document entitled "Rules of Civility & Decent Behaviour in Company and Conversation." (Among these rules: "Talk not with Meat in your Mouth" and "Kill no Vermin as Fleas, lice ticks &cc in the Sight of Others"). He also kept a record entitled "Where & How My Time is Spent." For a man of this temperament, any slaves' reluctance to hold themselves to similar standards was infuriating. As a younger man, Washington could complain about matters like "the deception with respect to the Potatoes." He could also be party to a slave raffle, documented by Mr. Wiencek, in which children could be won as prizes.

The breaking up of slave families for reasons of profit was, by Mr. Wiencek's account, the first outrage to penetrate Washington's self-interest. He traces Washington's first awareness of this to time he spent in Williamsburg, Va., witnessing slave auctions held in response to an owner's embezzling. "In modern terms, it was as if the collapse of a Wall Street brokerage, due to the malfeasance of its officers, had led to the sale of the children of the cleaning staff to pay the debts of corporate vice presidents," Mr. Wiencek writes.