If you are talking about John Donne, then it is his loved one's remark that he's leaving because he doesn't care for her anymore that motivates him to respond in the poem. He wants to answer to that remark and explain how things really are.
<em>The Grand Canyon came into view as I was hiking along the trail.</em>
<em>Walking toward the car, I could see that I had a flat tire.</em>
A misplaced modifier is a word, phrase or clause that is improperly separated from the word it modifies or describes. In the two sentences provided, the modifiers are correctly put next to the words they are modifying, making the sentences to have sense and not to sound confusing.
Every time you see you're, you should automatically know it's the joining of 2 words. Instead of reading you're, you should immediately think: "You are" So, read it by saying you are. Ichard told his song, you are young, but when you grow up, you'll understand (same with you'll, you'll is you will) You're is correct. Your is generally used as a possession term, normally with an item.