OCCUPY, MARSHALL GANZ ASKED: Is it a moment and a movement? Either way, it's the fastest growing phenomenon on the left in decades. If we add that its thrust — not its tactics, necessarily, but its slogan "We are the 99 percent," which was a nifty way to formulate opposition to the prevailing plutocracy — almost instantly garnered supermajority support throughout the country, then there may not have been anything like Occupy since the late 19th century movements against the robber barons. In the course of a month of human events, Occupy has whipped up an incandescent compound of joy, anger, hope, and resolve that shows no signs of fading and many signs of spreading. Emotions are not a movement, but they are its absolute prerequisite. Emotions have come out in the open. As in the sign above, from Foley Square in lower Manhattan, October 5.

If this is a moment before the literal and figurative winters kick in, it's an extended moment — one heading into its second month of occupations, which seem to number a few hundred people apiece (or fewer: a reporter told me that Occupy Nashville started with nine). They have been joined, rhetorically, and not always seamlessly, by unions, Moveon.org, various lobbies and liberal-left groups, along with freelance members of the self-declared 99 percent, when they foray outward to public spaces like Foley Square and Times Square. On Oct. 15, Occupy Nashville mustered hundreds; Occupy Wall Street, many thousands in Times Square. Hundreds — or is it thousands? — of solidarity demonstrations around the world: whatever numbers you trot out today — numbers of cities, numbers of occupiers — will be obsolete before the first frost.

So what is a social movement? In part, it's the sense of a movement: a tissue of feelings, thoughts, perceptions, and images. The feelings get entwined and complicated. All kinds of relationships develop, evolve and conflict. The minute you think you've got a movement pinned down it morphs.

But a moment doesn't become a movement until it continues — becomes a force, or a combination of forces. Almost always, in order to continue, it has to create institutions. It needs organizations, because individuals enter, exit, change and falter; the spirit, to endure, requires social bodies, structures that can outlast individual cells.

But movement isn't a thing. It isn't, itself, an organization. It doesn't have officers or headquarters. It's a verb seeking to be a noun, yet fearful of hardening at the same time, for noun-things solidify, and anarchic energy afoot wants to be liquid, not so much a thing as a process: an ensemble of moving parts, very much in motion, each drawing upon the others and pressing upon them, each making their moves in the light of what others do, an ensemble of movement actors. There's the inner movement, the outer movement, the politicians, the opposition — and, never forget, the police. They can do ...