A mystery, in Christian theology, is what God knows and man cannot, and must instead believe.

Nineteenth-century grass-roots populism made twentieth-century progressivism possible.

An ordinary life used to look something like this: born into a growing family, you help rear your siblings, have the first of your own half-dozen or even dozen children soon after you're grown, and die before your youngest has left home.

Fox News's coverage of 9/11 and the war in Iraq improved its ratings, demonstrated its influence, and intensified the controversy over its practices.

Old reference books are like tree rings. Without them, there'd be no way to know what a tree had lived through.

Germ theory, which secularized infectious disease, had a side effect: it sacralized epidemiology.

When I was a kid, my father would go to our school in the summer to sweep, mop, and wax the floors, room by room, hall by hall, week after week.

Weirdly, there have been a lot of critics of conservatism, but very few critics of innovation. As a culture, we are deeply paranoid about politics, but we gaze upon innovation with rapturous adulation.

History is hereditary only in this way: we, all of us, inherit everything, and then we choose what to cherish, what to disavow, and what to do next, which is why it's worth trying to know where things come from.

In antihistory, time is an illusion.

The study of history requires investigation, imagination, empathy, and respect. Reverence just doesn't enter into it.

History is only written from what remains.

Epidemiologists study patterns in order to combat infection. Stories about epidemics follow patterns, too. Stories aren't often deadly, but they can be virulent: spreading fast, weakening resistance, wreaking havoc.

Political elites vote in a more partisan fashion than the mass public; this tendency, too, follows a curve. The more you know, the more likely you are to vote in an ideologically consistent way, not just following your party but following a set of constraints dictated by a political ideology.

Secrecy is what is known, but not to everyone. Privacy is what allows us to keep what we know to ourselves.

In 1884, for the first time since the Civil War, voters had elected a Democrat to the White House. Grover Cleveland promised to use the government to protect ordinary Americans, and to stop congressmen from catering to wealthy industrialists.

Mt. Rushmore was conceived in 1923 in a desperate attempt to draw tourist dollars to a state that had been rushed into the Union to protect Republican political dominance and could not manage to achieve economic stability.

Since 1981, when President Ronald Reagan took office promising to scale back the federal government, Republican leaders have promised to cut regulation and taxes, and to return power to individuals to arrange their lives as they see fit. But they have never entirely managed to eradicate the New Deal government.

The Tax Cuts and Jobs Acts slashes taxes on the very wealthy and kills regulations with the idea that rich businessmen will invest their money into the economy to support workers - the same idea that Republicans embraced in the 1920s.

By 2015, the top 1 percent of families took home more than 20 percent of income. Wealth distribution was 10 times worse than that: the families in the top 1 percent owned as much as the families in the bottom 90 percent.

Republicans who controlled the government in the 1920s insisted that national prosperity depended on government protection of the rich, who they believed would plow their capital back into the economy to provide jobs and higher wages for workers.

Men like Abraham Lincoln recognized that if the slaveholders were not stopped, it would only be a question of time until they spread their system of elite rule to the entire country. Poor men would be bound for life into menial labor, and American democracy would die.

In the 1850s, as the numbers of Americans who were not invested in the slave system grew, the South's leaders felt they had to entrench their power in the government or it was only a question of time until lawmakers would begin to regulate, or even outlaw, slavery.

The fight is over two fundamentally different ideas about the nature of America. On one side are those who believe that that every hardworking person should be able to rise. On the other are those who believe that wealthy white men should always rule over a permanent class of workers.