John Cabanis begins with a rhetorical device called apophasis (also called paralepsis) in which a speaker brings something up by saying it should not be brought up. Politicians often use this as a way of pointing out their opponents' faults while stressing their positive differences from those opponents. For example, "I won't mention my opponent's terrible economic record, but I will point out my exemplary record."
Cabanis begins his epitaph addressing his "fellow citizens," a typical rhetorical device of putting him on equal ground with, not above, the people. Thus he is trying to be sympathetic. He then uses apophasis to address the problems with Spoon River (and maybe the country), but then says they are not the reason he left the party of "law and order" to lead the liberal party. These first six lines, an extended sentence in verse form, end with a period. We can hear the cadence because of the line breaks and the series of social problems. But these first lines must be more reserved relative to the next lines because he begins line 7 with a repetition of "fellow citizens," this time with an exclamation point. The crescendo begins, and he continues to rise with criticisms, so his emotional state begins calm and negative and rises to energized and negative.
From here, the cadence rises, becomes more emotional, and could be interpreted as a rousing political speech or a combination of political/spiritual style in the manner of someone like Dr. Martin Luther King, Jr. His tone also changes as he moves from describing the problems in society to describing his moment of enlightenment, a more hopeful statement: "I saw as one with second sight . . ."
However, the tone shifts again to negative as he lists the problems he sees with his "second sight." Again, he lists "lawlessness" and the fact that every man who fights for freedom dies trying to build a foundation for a "temple." The temple likely refers to a mythic version of America and/or the town. Although the oratory may be increasingly vehement (due to the exclamation point), his criticism is still focused on the negative.
But Cabanis finishes with statements of hope. Although he has only seen lawlessness and weak and blind rulers, he believes freedom will inevitably prevail and every man (person) will achieve the wisdom of a philosopher king.
And I swear that Freedom will wage to the end
The war for making every soul
Wise and strong and as fit to rule
As Plato's lofty guardians
In a world republic girdled!
Note the finish with the exclamation point. The poem can be divided into three segments: the first is a statement and the next two are exclamations. This indicates a crescendo. Cabanis starts with statements of negative criticism. He raises the energy with "Fellow citizens!" and begins describing his "second sight," implying an enlightening experience. The tone shifts momentarily to this hopeful enlightenment, but then moves back to the negative criticism. He shifts tone again, ending with the hope that freedom will inspire everyone to become as wise as Plato's philosopher kings, the wise and strong rulers in Plato's utopia. Overall, the poem is a transition from negative criticism to optimism for the future. As indicated by the punctuation, the energy increases like a politician's or a religious leader's rousing motivational tone.