Question about College Essays...Now I'm really confused!!!

<p>I've heard that you're supposed to write about something you're passionate about, but then I also heard you're supposed to write about something that isn't mentioned in another part of your application, so that the admissions officers can learn something new about you. But if you write about something you're passionate about, it would probably end up being in some other part of your application, so is it better to write about something you're passionate about, or reveal some defining personality traits through a story or event not shown anywhere else in your application?
thanks!</p>