get to the heart of (something)

To discover, determine, and/or understand the essential, core, or most important aspect(s) of some issue, problem, or topic at hand. Don't worry ma'am, we'll get to the heart of the matter of your daughter's disappearance. After two hours tinkering with your computer, I think I've gotten to the heart of the problem. Her latest novel really gets to the heart of what it means to be human.