I recently asked a friend of mine who happens to be a medical doctor, “Who is in charge, the heart or the brain?” He said, the brain and I said, “I am going to challenge you on that one! You can find many people in the hospital who are still alive - clinically brain dead, but when the heart stops, it’s all over.”
I think that if we look metaphorically at the brain and head, then the brain is mental and the heart is emotional. And if we put them together in harmony, we will have the mental and the emotional - one starts with “M” and the other with “E”, when we put them together we have “ME” and nobody can mess with “ME”.