It is the nature of protest movements that they must either expand or wither away: they can never stand still.

The current Wall Street protests, originally conceived of as an "occupation," are attempting to

maintain their momentum by expanding their numbers, occupying more territory, and generating clashes with the police.  They are now approaching the point of critical mass, where they will either swell into a mass movement that brings about significant change, as did the Civil Rights movement of the 1950s, or simply dissolve and disappear.

Protest movements operate out of their own internal dynamic.  They swell in numbers in response to perceived injustices; they fade away if they cannot retain momentum.  As the great social psychologist Elias Canetti wrote of gatherings of this sort, "[e]verything here depends on movement" (Crowds and Power, 1984, p. 30).  Absent a sense of movement toward a goal, the Occupy Wall Street protest and similar protests in other cities will soon disintegrate.

Having gathered significant numbers in New York and other cities, the protest now finds itself at this critical juncture.  The crowds that have gathered to protest "corporate greed," as they imagine it, are of necessity moving beyond occupation and toward a more aggressive stage of protest.  The "occupation," in other words, is no longer an occupation, but instead an assault.

In New York, Boston, and Washington, it is clear that the protests have entered this second stage.  On September 24, Occupy New York began to turn violent as police were forced to control the disorderly crowd, and eighty protesters were arrested.  On October 5, also in New York, hundreds of protesters stormed a police barricade, forcing police to respond with pepper spray and leading to further arrests.  Moving from its sanctioned location in Zuccotti Park, the mob has attempted to shut down traffic and cause disruption in heavily frequented parts of Manhattan, including the entrance to the New York Stock Exchange and the approach to the Brooklyn Bridge.  It has carried its protest to the Upper-East-Side residences of prominent New Yorkers, particularly those associated with conservative politics, such as Rupert Murdoch and David Koch.

It is not just in New York that the protests have turned violent.  On October 11, one hundred protesters were arrested in Boston when they refused to comply with police instructions to leave the Rose Kennedy Greenway.  Similar violence has been reported in Seattle and Washington, where protesters stormed the Smithsonian's National Air and Space Museum.

Granted, many of these young protesters seem clueless as to what they are about.  Many seem to be protesting for the sake of doing so, as if the protests were a pleasant little summer camp and not a serious political statement.  But there is also the sense of darker forces at work behind the scenes.  The hapless young people who initiated Occupy Wall Street have been joined by hard-line leftists, union thugs, and lawless radicals intent on inciting violence.  As was the case with the Arab Spring, zealous revolutionaries have their eye on what may have begun as an incoherent gathering of disaffected youths.  These more organized elements are determined to move the protests toward a third stage.

What is the third stage?  Lawlessness, violence, and terrorism.

This is not the first time that a peaceful protest movement has turned violent.  In the spring of 1969, at the height of the antiwar protests in the United States, I had occasion to meet Mark Rudd just at the time when Rudd, along with other leaders of Students for a Democratic Society, were organizing the Weathermen, a leftist terror organization.  Of my fleeting encounter with Rudd I remember little, except that he was so completely cocooned within the stilted rhetoric of the left that he seemed more an automaton than a person.

The Weatherman "Declaration of a State of War" against the United States makes for interesting reading.  The Declaration was the ideological basis for a series of bombings of government and corporate buildings, including a bombing of the Pentagon on May 19, 1972.  It was originally proclaimed by Bernardine Dohrn, wife of Bill Ayers and confidante of our current president.

In this declaration of struggle against "Amerikan imperialism," the Weathermen called for nothing less than "destruction of the [American] empire."  The key passage in the Declaration is the statement that "[t]ens of thousands have learned that protests and marches don't do it. Revolutionary violence is the only way."  The Declaration emphasizes that at the critical point in its development, the protest movement must turn to violence in order to sustain itself.  It must move "underground," where it will become a terror organization.  It revels in the possibility of tens of thousands of alienated "kids" -- "making love, smoking dope and loading guns."

As this passage makes clear, SDS had reached the point where it decided, quite consciously, to embrace violence.  This was the third phase of the antiwar movement, and it was inevitable, given the waning interest in the movement following the 1960s.  Most young people had better things to do than to "blame the system," and as they turned their backs on the left, the SDS responded by intensifying its efforts.  Thus, the Weatherman Underground was born.

Occupy Wall Street has not yet reached this point of development, and hopefully it will disperse before doing so.  But, clearly, it is evolving beyond a small ground sleeping out in the park and making its points with signs, speeches, and internet posts.  It is now moving toward the second stage, where larger numbers or dramatic acts of protest are necessary to sustain momentum.

What happens next bears watching closely, as does the response of the president, ex-Speaker Pelosi, and others on the left.  Encouraged by leftists in the Democratic Party and funded by left-leaning nonprofit organizations and celebrity contributors, Occupy Wall Street may in time morph into something resembling the radical factions of the late 1960s and 1970s.

If they do so, those who have aided and encouraged them should be held accountable.  Then it will not be just Ayers and Dohrn with blood on their hands.  It will be their young protégé in the White House as well.

Jeffrey Folks is the author of numerous books and articles on American culture.