The focal, central, or most important element of a topic, problem, or issue. Over the course of this trial, the prosecution intends to get to the heart of the matter regarding this company's shady financial dealings.
the central issue of the matter. (Crux is an old word meaning "cross." *Typically: be at ~; get at ~; go to ~; look at ~.) All right, this is the crux of the matter.It's about time that we got to the heart of the matter.