The world is charged with the grandeur of God.
It will flame out, like shining from shook foil;
It gathers to a greatness, like the ooze of oil
Crushed. Why do men then now not reck his rod?
Generations have trod, have trod, have trod;
And all is seared with trade; bleared, smeared with toil;
And wears man's smudge and shares man's smell: the soil
Is bare now, nor can foot feel, being shod.
The repetition of “have trod” forms three iambs, where a iamb is a metrical foot comprising one unstressed followed by one stressed syllable. This could be said to imitate plodding footsteps, wearing down the reader’s ear, preparing for the folly of man in the following description. 
 Additionally, this repetition could also reflect Hopkins' questions about the “Generations” that have ignored the grandeur of God.