Your medical school personal statement needs to sell. Every single word has to sell your reader and answer the question: "Is it worth my time to read one more word of this essay?" To be persuasive is to sell your reader on your next sentence, your next paragraph, your next idea of your medical school essay.
Using a single basic theme is one method you can employ to guarantee your essay's coherence and effectiveness. It forces you to organize your thoughts and ideas and helps keep the essay focused. Without a theme, your essay will simply look like a haphazard collection of facts thrown together to impress the reader. With a main theme, the essay will have a focal point upon which you will develop the rest of the paragraphs.