Thomas Mann came to the United States when his native Germany went under Nazi control. Among the many things he wrote was this comment on democracy:

"Democracy is a means of living together despite our differences. Democratic deliberation is an alternative to physical violence. It is predicated on the assumption that it's possible to disagree agreeably … that one can vigorously contest the position of one's adversary without questioning his or her personal integrity or motivation, and that parties to a debate are entitled to the presumption that their views are legitimate if not correct."

Those principles should guide people writing letters to the editor. Publishing letters that address public issues is one of the Tribune's important functions.

Many of the letters are impassioned, sometimes indignant over a matter the writer reckons to be an injustice.

But they must be civil, or they won't be seen in print.

Especially as we approach an election, people should be reminded of the importance of civil discourse in a democracy. The media often are accused of allowing mudslinging, when people become weary of a barrage of attack-counterattack. Readers should be assured that most editors have an aversion to mud - especially at the end of a day of wading in it. Reading an opinion page editor's e-mails would overwhelm anyone who's fastidious.

There is a place for vigorous debate in the letters to the editor space. In a healthy democracy, it's positive to disagree agreeably. It is the opposite to seek to inflict wounds.

A requisite for writing a letter to the editor is this: Speak to the editor. Do not write an open letter to the mayor or the congressional delegation. Do not address a previous letter writer as if speaking to that person - "Concerning Franklin F. Flapdoodle's Nov. 28 letter to the editor, Flapdoodle, you're an idiot."

No.

In point of fact, writers shouldn't address the editor with their opinion Flapdoodle is an idiot. No name-calling allowed. It's bad enough that kind of thing happens on talk radio. Be decent. Writers should try to be civil, even when writing about matters they consider to be beneath contempt. A citizen might be convinced that abortion is morally evil, but a letter writer doesn't need to say that a woman who has one or a physician who performs one is an evil person. Furthermore, there is a line, sometimes difficult to draw, between making critical commentary - fair comment - about a person in a role as a public figure and criticizing individuals who definitely should never be defamed.

Letters to the editor serve an important purpose in the life of a newspaper and the life of a society. Having one be considered and printed is an important privilege. Note: Privilege, not a right. A newspaper offers its space, inviting readers to participate in the precious process of communication.

The art of civil discourse in a democracy must be valued and practiced. Let's hope candidates for elected office can make it happen during coming months.