As a movie, Steven Spielberg’s “Lincoln” succeeds only imperfectly, but as an introduction to the practice of democratic government, it is a triumph.

“Lincoln” opens with the Gettysburg Address and closes with his second inaugural address, two speeches every American should cherish.

The recitation of those speeches and Daniel Day-Lewis’s marvelous performance, which perfectly embodies the Abraham Lincoln formerly known only to historians, guarantee that the film will be required viewing in American middle schools for years to come.

For viewers past their school years, the movie’s lessons run deeper. Its central drama reminds us that the fundamental task of democratic politics is persuasion: To enact legislation, majorities must be persuaded to vote for its passage, and the losers must be persuaded to accept the result.

The Civil War stands as a stark reminder that the second task is more important than the first. In his first inaugural address, not shown in the film, Lincoln sought unsuccessfully to persuade the people of South to accept his presidency. He failed. And the war came.

In the film, Lincoln confronts two problems of persuasion. It is January 1865, and, having just won re-election, he is trying to persuade members of the House to vote for the 13th Amendment to abolish slavery. Looking forward to the end of the war, he is beginning the task of persuading the rebels to rejoin the Union and to accept the end of slavery.

Though we remember Lincoln for his great speeches, the film reminds us that he was no great orator and that the power of his speeches did not derive fundamentally from their beautiful words.

In the opening scene, an ordinary soldier tells the president he was there when Lincoln spoke at Gettysburg and was moved by his words. Lincoln asks whether the soldier had actually heard the speech. He hadn’t, but had read the words in a newspaper and learned them by heart.

The beautiful words make the speech more memorable, but its power lies in the argument, which advances a simple, clear agenda, supported by compelling moral and practical reasons.

The Civil War, Lincoln argues, is a test of whether a nation conceived in liberty and dedicated to the proposition that all men are created equal, can long endure. Those who died at Gettysburg died to prove that democratic government was possible — is possible — and Lincoln calls upon his fellow citizens to take increased devotion to that same cause, to resolve and to fight so that the United States shall experience a new birth of freedom.

The film demonstrates the power of Lincoln’s speech by depicting its effects on men it had persuaded to act and instilled with moral purpose.

It also reminds us that Lincoln had an acute sense of what people could be persuaded to accept and when.

Accused by the firebrand Republican Thaddeus Stevens of being insufficiently principled, Lincoln replies that he had always held to the same, core principles, but moved carefully and sometimes obliquely to advance them by concrete steps as best he could.

At his inauguration, Lincoln strove to save the Union to vindicate the possibility of majority rule and to demonstrate the possibility that ordinary people could govern themselves without falling into anarchy or despotism. But he knew, then, that he could not succeed in advancing the principle of equality any further, by acting against slavery.

By 1862, when he wrote the Emancipation Proclamation, he understood that his loyal fellow citizens in the North would accept it as a necessity of war; the conflict had by then been so fierce and so bloody, they would accept a step that promised a measure of equality to African Americans, despite their widespread racial prejudices.

By 1865, when emancipation had been temporarily accomplished throughout much of the South, Lincoln understood that the time was right to persuade people to accomplish that new birth of freedom by abolishing slavery through constitutional amendment.

Though he was the greatest man of his age, Lincoln wasn’t proud. Accepting the fact of equality means recognizing that other people have their own minds, and that we will not all think alike on every issue. He spoke personally with wavering congressmen; he was unruffled by the most intemperate personal criticism; he was willing to make deals to get the votes he needed.

Lincoln reminds us that democratic persuasion is a hard business, requiring not only moral clarity, but also humility, intelligence and patience.

All of which, alas, seem to be in short supply in Washington today.

Joseph R. Reisert is associate professor of American constitutional law and chairman of the department of government at Colby College in Waterville.