The moderate Republicans with whom Bush served as a congressman, and among whose ranks he felt ideologically comfortable, have all but vanished. Consider this astonishing Meacham statistic: As a House member in the 1960s, Bush backed Johnson-supported bills 53.5 percent of the time. After Nixon took office, that support scarcely budged. Bush himself not only voted for the Fair Housing Act, he also supported family planning, bilingual education and an expanded Head Start.

The mechanisms and realities of modern politics — the slashing 24/7 news cycle; the sorting into partisan factions that consume only media with which they agree; the powerful arsenal of super PACs and other tools of modern campaign finance warfare — all find their roots in Bush’s presidency.

“He was a creature of one Washington who inadvertently presided over the creation of another,” Meacham said at a recent book talk.