"...the thoughts and intents of the heart."

Proverb's injunction that "as a man thinketh in his heart so is he" is an interesting proposition.  Does a heart think?  Don't we usually assign the thinking part of our being to the brain?  Religion is most often concerned with the heart above and beyond the mind when it comes to judging the character of a man or woman.  

 As Jesus said,  "But those things which proceed out of the mouth come forth from the heart; and they defile the man."  (New Testament | Matthew 15:18)  "Wherefore think ye evil in your hearts?"  (New Testament | Matthew 9:4)

Hebrews uses the term "the thoughts and intents of the heart." (New Testament | Hebrews 4:12)

That phrasing is used multiple times through out the Book of Mormon and then again in the Doctrine and Covenants. The scriptures almost 100% refer to the heart as the thinking organ and usually in relationship with one's intent or purpose.  

Intention is at the core of our being.  We may cover our intention by appearing to be one way when really in our core we intend something else.  We may even be adept at deceiving ourselves as to our true intentions unless we are willing to give ourselves an honest and frank evaluation.  But as the scriptures tell us God sees into our heart and discerns our intent. That is the fairest of all judgments.  

Science is beginning to catch up with religion on the matters of the heart.  Research is finding that indeed the heart which is composed of more neuron cells than muscle cells does have an intelligence and that it does communicate with other parts of the body including the brain.  The heart is the first organ to function after conception, within about 20 days.  The brain does not function until after 90 days or so.  

Research at the Institute of Heart Math indicates that:

 "The heart is the most powerful generator of electromagnetic energy in the human body, producing the largest rhythmic electromagnetic field of any of the body’s organs. The heart’s electrical field is about 60 times greater in amplitude than the electrical activity generated by the brain. This field, measured in the form of an electrocardiogram (ECG), can be detected anywhere on the surface of the body. Furthermore, the magnetic field produced by the heart is more than 5,000 times greater in strength than the field generated by the brain, and can be detected a number of feet away from the body, in all directions, using SQUID-based magnetometers." 

"As a man thinketh in his heart" seems to be more than just symbolism.