They're alive! Or at least the lines are moving. In order to give each stanza the shape of a wing, Herbert has to first axe out two syllables every line and then add 'em back in a few lines later. (For more on how this fits with the poem's rhythm, check out "Form and Meter.")
But this isn't careless hacking. Give it a closer read and you'll notice that the lines describing the greatest comfort and the greatest hope are also the longest (1 and 10, 11 and 20), while those that chronicle the moments of greatest despair and the faintest hope are the shortest (5 and 6, 15 and 16). Each line of the poem responds in a careful, intimate way to the content of that line.
Lines 1 and 11: The four longest lines of the poem, at 10 syllables each, correspond with the poem's happiest moments. At line 1 it's the creation of Adam in all his original abundance. Line 11 doesn't seem too perky at first glance, but compared to what's in store for the speaker in lines 12-15, it's relatively in great shape.
Lines 10 and 20: What about the final lines of each stanza? These also look a little down, since 10 mentions the "fall" and 20 chimes in with "affliction." But these are also paradoxes. There's no question that both the fall and affliction are bad—bad for Adam, bad for the speaker, bad for everyone. But precisely because they're so bad, they allow the speaker to experience an even greater transformation. If he hadn't fallen so low, he'd never have to rise so high. And that flight is itself a good thing for the speaker, an opportunity to hang out with God and feel his love. For more on how weakness is opportunity, check out "Weakness" under the "Themes" tab.
Lines 5-6, 15-16: These four lines are the shortest of the poem, only 2 syllables a piece. They're also the grimmest. Lines 5 and 6 mark the lowest points for Adam and the speaker, while lines 6 and 16 offer only the first feeble flickers of hope.