Did your teacher use a rubric to grade? It sounds like it, since you said 4 out of 6. Look carefully and the rubric, and see where specifcally you lost points. I agree with the above to a certain extent, but I don't really see a conclusion problem alone dropping you from to a 4.
First, I must say that I am impressed with you choice of words. It is certainly elevated for a student in the eleventh grade (I have read college papers which were not as elegant). Outside of that, I would have to say that your closing paragraph does not mirror the flow and concise manner of the previous paragraphs. (It seems rushed and, therefore, the elevation of the language drops.) While still filled with wonderful words, it (for me) does not seem to be the same caliber writing as the rest of the essay.
Also, there are some grammatical errors (Run-ons and missing punctuation).