lie at the heart of (something)

lie at the heart of (something)

To be the central part or most crucial element of something. What are the issues that truly lie at the heart of the homelessness crisis? Until we identify and account for those, we cannot suggest meaningful, long-term solutions. I suspect that grief lies at the heart of his angry outburst. It's only been a few months since his brother died, after all.
See also: heart, lie, of
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.