Parallelism is defined as using elements in sentences that are grammatically similar or identical in structure, sound, meaning, or meter. For example, referring to Brooke’s poem:

“That there’s some corner of a foreign field/That is forever England. There shall be/In that rich earth a richer dust concealed”

Try reading this sentence out loud to hear what it sounds like. There is a cadence to “that” and “there” that is being repeated. Also, “rich” and “richer” are used to the same effect.

In another example:

“A dust whom England bore, shaped, made aware/Gave, once, her flowers to love, her ways to roam”

Take a look at the verbs used in this line: “bore,” “shaped,” “made aware.” Each is in the same tense which is a good indicator of parallelism. To give an example that is NOT parallelism, the line would read:

“A dust whom England bore, shaping, making aware, gave, once, her flowers, to love, her ways to roam.”

See how the tense of the verbs changed? Some are present tense, while others are past tense. The poem doesn’t sound as musical formatted this way. But, in Brooke's poem, he is careful to use the past tense to maintain parallelism, and overall, give a more enjoyable reading experience.  However, “to love” and “to roam” is another example of parallelism. Here is a last example for you:

“Give somewhere back the thoughts by England Given/In hearts at peace, under an English heaven”

It is clear that “given” and “heaven” are rhymes. But, the meter in which this poem is written is what lends itself to parallelism. That means this stanza qualifies as parallelism because of how similar both words sound. The entire poem follows a similar pattern or structure which, essentially, makes this poem in and of itself, a parallelism.