There are, of course, many different ways of categorizing historical revolutions. But for the purposes of understanding what is happening in Egypt -- and the challenges it may pose for the United States -- one simple, rough distinction may be especially useful. This is the distinction between revolutions that look more like 1688 and revolutions that look more like 1789. The first date refers to England's "Glorious Revolution," in which the Catholic, would-be absolute monarch James II was overthrown and replaced by the Protestant William and Mary and the English Parliament claimed powerful and enduring new forms of authority. The second is, of course, the date of the French Revolution, which began as an attempt to create a constitutional monarchy but ultimately led to the execution of King Louis XVI, the proclamation of the First French Republic, and the Reign of Terror.
A key feature of 1688-type revolutions is their relative brevity. They may be preceded by lengthy periods of discontent, agitation, protest, and even violence, but the revolutionary moment itself generally lasts for only a few months (as in 1688 itself), or even weeks or days. A regime reaches a point of crisis and falls. The consolidation of a new regime itself may well involve much more turmoil and bloodshed, and eventually entail considerable political and social change -- but these later events are not considered part of the revolution itself, and there is no sense of an ongoing revolutionary process. Men and women do not define themselves as active "revolutionaries" (in 1688, in fact, the English noun and adjective "revolutionary" did not yet exist -- it only came into frequent use after 1789).
Revolutions of the 1789 type are quite different. Their leaders and supporters see regime change as only the beginning of an arduous, ambitious process of political, social, and cultural transformation that may require years, even decades, to complete. For them, the revolution is not a discrete event, but an ongoing cause. They eagerly define themselves as "revolutionaries" and even speak of the "permanent revolution." Revolutions of this type generally have much stronger utopian tendencies than the others and more frequently lead to large-scale violence. They also tend to have ambitions that overflow national boundaries -- the local revolution becomes seen as just part of a process of worldwide emancipation. In some cases, revolutions of this type may be driven from the start by a self-consciously revolutionary party, committed to radical upheaval. In other cases (such as 1789 itself), it may seem to start off as a more limited event, only to change its character as particular groups grow frustrated with the results and the opposition they have encountered, and conclude that far broader, deeper forms of change are called for.
Historically, 1688-type revolutions have been much more common: France in 1830, Germany in 1918, China in 1911-12, and many of the revolutions of 1848 (of which most ended in failure). 1789-type revolutions, by contrast, have been relative historical rarities: above all, 1789 itself, Russia in 1917, China in 1949, Cuba in 1959. They are not, however, necessarily revolutions of the left. One could also include in this category the Nazi seizure of power in Germany (which Hitler termed a "National Revolution") and Iran in 1979. The American Revolution, it could be argued, represents something of a hybrid case -- closer to 1688, yet with important features of the other type, thanks to the long process of consolidation and contestation that followed independence.
In recent years, it seems as if the 1789 type of revolution has lost its appeal for most of the world. During the greatest series of political upheavals in recent times -- the collapse of communism -- most leaders of the victorious reform movements rejected the word "revolution" altogether. The Polish Solidarity leader Jacek Kuron went so far as to write in the summer of 1989, apropos of the French Revolution's bicentennial, that Poland did not want a revolution because revolutions spill too much blood. Germans refer to the events of 1989 as the "Turning," not the "Revolution." It was, above all, in Czechoslovakia that the word "revolution" came to describe what happened in 1989, but paired with the word "velvet" to underscore the differences from the great revolutions of the past.