“Yon Cassius has a lean and hungry look, he thinks too much. Such men are dangerous. … Yet if my name were liable to fear, I do not know the man I should avoid, so soon as that spare Cassius. He reads much; he is a great observer; and he looks quite through the deeds of men.” — Julius Caesar

In stage performance, tragedies are marked by many common themes. One of those is a lead character, a person of power, who becomes increasingly paranoid and begins seeing enemies everywhere.

Such neuroses famously afflicted characters like Julius Caesar, Macbeth, Hamlet and Othello. The irony is that in acting on their own paranoia, such people take steps toward tyranny and wind up creating the very situations and feelings they fear.

On stage or film, it makes for great drama.

In real life, involving real people in positions of power, it can be frightening.

As part of his re-election campaign, Barack Obama has posted on his websites a page called “Behind the curtain: A brief history of Romney’s donors.” In it, he singles out individual wealthy donors and demonizes them for contributing to the Romney campaign and “betting against America.”

He basically casts the Romney donors as evil for everything from making money from oil investments to being against gay marriage. He implicates several of them in criminal activity.

Politics can get dirty. But no president since Nixon has blatantly abused his power to intimidate individual Americans. The reason Nixon’s “enemies list” was so shocking and outrageous is precisely because of the power of the presidency. A president can have people imprisoned, investigated, harassed and impoverished — all legally.

Most presidents are aware that such power must be controlled by the one who wields it. This president has no such restraint.

The Obama administration has been marked from the beginning by a paranoid obsession that probably goes hand in hand with the president’s clear narcissism.

Even before he was elected, the Obama campaign had teams of people scouring the Internet trying to counteract negative talk about the candidate by burying posts, voting down blogs and even getting stories buried or killed.

Since tbe Obamas moved into the White House, it has only gotten worse. Recently, some of the media admitted pulling a story about Malia Obama vacationing in Mexico at the White House’s request.

There is a full-time crew working under a director of Progressive Media and Online Response, charged with cleaning up the boss’s Internet image and, more importantly, monitoring die-hard opponents.

In the early days of the White House occupation, Obama’s Department of Homeland Security issued a public report about a supposed rising threat from “right-wing extremist” groups, lumping conservatives in with nazis (left-wingers) and the Tea Party with the Weather Underground (Obama’s former patrons).

The report was a broad swipe at conservatives that cited fabricated “resurgence in rightwing extremist recruitment and radicalizations activity” because of home foreclosures, the state of the economy and, of course, the historic election of a black president.

The DHS even went so far as to implicate returning war veterans as potential terrorists to be recruited by conservative groups.

The president’s paranoia has infected not only his administration, but has fed the worst elements of his entire party, as can be seen in almost any reading of the New York Times. Throughout the major media, the story is the same: Conservative equals evil.

Increasingly, everyday people are being recruited by this administration and Democratic-run governments at all levels to act as spies and stoolies. The IRS offers a reward to anyone who turns in a neighbor who cheats on taxes. Newark, N.J.’s mayor wants people to turn in neighbors for owning guns.

The growing paranoia is evident in the ridiculous levels of security at airports, at government offices and even in the amount of background checking you may have to go through to get a job.

But history and art teach us something about regimes on such a path. Their paranoia always grows, resulting in worsening tyranny until they reach a critical point where they either become a full-fledged dictatorship or the tyrants are overthrown by a populace that is fed up with feeding the egotism of a despot.

With the re-election fast approaching, could that breaking point be coming up as well?