Don't strain the cord until it snaps, don't split the sound heart with your wedge how do the lines in bold develop the main point or theme of the poem?

In this poem, the author warns "Helen Grey" or being overly confident. The author tells her that she is loved now, but that she should not take too much comfort on that. She is beautiful, but she should not be overly proud, as in time, old age will come and men will forget about her. Therefore, she should not be so arrogant, and she should instead appreciate what she has now. The lines in bold emphasize the idea of being careful that you are not in the way of your own happiness.

this is b. how railways dealt with people riding the trains without paying

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