Note the off beat, weak, fading metre of the last line. The first stress is on that and the line fades to the next stress on all and again fades to dif. And notice also the onomatopoeic effect of difference like the sound of air gently escaping from a floating balloon. It's a poem about bombast, bluster, beauty and opportunity squandered, , fumbling, poorly constructed decisions and, at the end, sinking and failure - not by a long shot, not about triumph and success. America, the great man is pulling your leg.
I have often looked out on a mountain range where the foothills fold on fold ascend; and I have imagined the unique magic of each hidden valley. The repetition of the last two lines reminds me of that. As any young child will testify, there is beauty in repetition - and each repetition is somehow unique.
The poem as a whole to me resonates with the transfiguration story ((Mark 9: 2-6) .Behold it is good for us to be here - - - but he knew not what he said. The journey is far from over.