To answer this question, we should first look at the definition of syntax. It is defined as...
...the study of the patterns of formation of sentences and phrases from words.
In simple terms, the syntax of a sentence refers to the order in which the words are placed. For a poet, grammatical rules are often ignored in order to create a pattern of rhyme (rhyme scheme). Wordsworth's "The World Is Too Much With Us" is a Petrarchan (Italian) sonnet, made up of 14 lines, following a predetermined pattern of rhyme. In this case it is:
abba abba cd cd cd
On a basic structural level, we can see how Wordsworth uses the syntax of a line to follow the pattern of rhyme. In "abba," the "a" represents one sound, and the "b" represents another. This means that the first and fourth line must rhyme as well as the second and third lines. The second line ends with the word "powers," so the end of the third line must rhyme with that. The author uses "ours" to rhyme with "powers," however, the syntax might represent a sentence structure that is unfamiliar or awkward to the modern reader. Wordsworth writes:
Little we see in Nature that is ours...
Without a rhyme scheme in mind, we might write:
This is little that is ours that we can see in Nature...
This is a structural technique or trick often seen with songwriters as well as poets. However, at the same time, one might argue that there is more here than meets the eye. Perhaps Wordsworth uses the syntax, or word order, to support the theme of his poem: this kind of sophisticated writing would not be at all unusual for the Romantic poets (of which Wordsworth was one). His theme is that the modern world intrudes in a terrible way—so much so that we have lost sight of the wonders of the natural world.
The poet begins the poem telling the audience what the problem is:
Comprehensively, totally, utterly, the poet opines, people are captives of the world they seek to understand or control.
"Getting and spending" and "waste our powers" are phrases that speak to society's tendency to throw away those valuable aspects of our natural world and existence in order to pursue a world that has left nature behind. In doing so, he notes, "We have given our hearts away."
For the first nine lines, the author seems to present an important element regarding what is important in life, to follow at the end of that line what exists instead of the valuation of nature. "Getting and spending," for instance, sound like positive things, but by the end of the line, the cost is too great—for "we lay waste our powers." "Little we see in Nature" points out that Nature should be emulated and prized, but the end of the line notes that it is not ours: we have lost it...given it away.
By the middle of the ninth line, Wordsworth turns the syntax to show "what if." The important image noted as the line starts contrasts directly to what might be if we turned our eyes back to nature. In line 11, for example, choosing a different tack, one could instead be "standing on this pleasant lea." And...
Have glimpses that would make me less forlorn...
The syntax at the poem's beginning shows the danger of turning from nature and immersing oneself in the modern world. The syntax in the poem's last lines (where the author generally provides a resolution to the conflict presented at the poem's start) now starts with the reality, followed at the line's end by the possibility of a "return to nature," a common Romantic theme.