When can I use the expression "the heart of something"?
Native speaker’s answer
Rebecca
To be at the heart of something is to be very important, influential, or be the foundation or something. So you can use "the heart of something" when that thing is a key issue in the situation or a key part of what you're talking about. Ex: He was the heart of the reason why I decided to move. Ex: Let us get to the heart of the discussion.