Answer:
From the excerpt, what I understand is that a revolution begins with a stubborn determination that is fuelled by the optimism for change.
This stubborn optimism leads to an organized action agitating for that change, the optimism for change sustains the agitation for change and reform.
Without the stubborn optimism for change, the action would surely wane and die because without something to believe in and hope on, there would be no action to instigate change.
Likewise, if there is a stubborn optimism for change without corresponding action, it is just seen as an attitude but combining both together - the optimism for change and action -, a lot of things can be changed.