Deductive thinking moves from general principles to specific instances. Often, as in a thesis/support essay, prose writers make a general claim and then use specific details and examples to illustrate and back up their point.
A poem's form is partly visual: its look on the page. George Herbert's "Easter Wings" is an example of striking visual form, as is e. e. cummings' "r-p-o-p-h-e-s-s-a-g-r." But visual form also works in less obvious ways. The lean, spare look of most Emily Dickinson poems complements her terse style, while the long, sweeping lines of Walt Whitman accentuate his bold, expansive message.