In The Rise of Democracy, Sean Wilentz offers an interesting definition of democracy (and its vulnerability):
"Democracy appears when some large number of previously excluded, ordinary persons--what the eighteenth century called the many--secure the power not simply to select their governors but to oversee the institutions of government, as officeholders and as citizens free to assemble and criticize those in office. Democracy is never a gift bestowed by benevolent, farseeing rulers who seek to reinforce their own legitimacy. It must always be fought for, by political coalitions that cut across distinctions of wealth, power, and interest. It succeeds and survives only when it is rooted in the lives and expectations of its citizens and continually reinvigorated in each generation. Democratic successes are never irreversible" (xix).
This first sentence, what rhetoricians or cranky English teachers might call a loose sentence (loose, meaning the sentence begins with its main independent clause but then meanders on through a series of dependent clauses or phrases), defies the current conventions of popular writing and the advice of most Engish teachers by piling ideas, clauses, and phrases on after its main clause. What would not work for many lesser writers (myself included), works wonderfully for Wientz because the litany of verbs and the appositive phrase set off by dashes qualify and explain the author's definition of democracy.
The first sentence also works because the writer follows this long, complex sentence with shorter, punchier sentences marked by anaphora ("It must always be faught for...It succeeds and survives...") and energetic verbs: "fought," "cut," "succeeds," "survives," and "reinvigorated." When the clincher sentence reminds us that democracy is "never irreversible," the sudden turn from the rhetorical dynamism of this series of verbs adds drama to the foreboding prediction about the vulnerability of democracy.
In short, the long first sentence and the two short sentences set up the crucial shift of logic and meaning in the clincher sentence. Sentence variety and action verbs work their magic.