"Keep your heart with all diligence,
For out of it spring the issues of life." Proverbs 4:23

The word heart in the Bible has a broader meaning than it does to the modern mind. The heart is seen as the main organ of physical life.
Vine's Expository Dictionary says,
"By an easy transition the word came to stand for man's mental and moral activity, both rational and the emotional elements. In other words, the heart is used figuratively for the hidden springs of the personal life."

The heart contains the hidden man/woman; the real person. 1 Peter 3:3-4 speaking of wives, but men are included also, "And let not your adornment be merely external...but let it be the hidden person of the heart, with the imperishable quality of a gentle and quiet spirit, which is precious in the sight of God."

The New Testament speaks of the heart--
As the seat of moral nature and spiritual life:
"Let not your heart be troubled; believe in God, believe also in Me."
John 14:1

As the seat of love:
"And you shall love the Lord your God with all your heart, and with all your soul, and with all your mind, and with all your strength." Mark 12:30

As the seat of grief:
The Apostle Paul is speaking to the Corinthians in his second letter to them, "For out of much affliction and anguish of heart I wrote to you with many tears; not that you should be made sorrowful, but that you might know the love which I have especially for you." 2 Corinthians 2:4

As the seat of joy:
Jesus to His disciples in His farewell discourse, "Therefore you too now have sorrow; but I will see you again, and your heart will rejoice, and no one takes your joy away from you." John 16:22

As the seat of desires:
In His Sermon on the Mount, Jesus says,
"You have heard that it was said, 'You shall not commit adultery'; but I say to you, that everyone who looks on a woman to lust for her has committed adultery with her already in his heart." Matthew 5: 27-28

As the seat of affections:
The response of the two disciples on the Emmaus road after they recognized Jesus, "And their eyes were opened and they recognized Him; and He vanished from their sight. And they said to one another, 'Were not our hearts burning within us while He was speaking to us on the road, while He was explaining the Scriptures to us." Luke 24:31-32

As the seat of thoughts and intentions:
"For the word of God is living and active and sharper than any two-edged sword, and piercing as far as the division of soul and spirit, of both joints and marrow, and able to judge the thoughts and intentions of the heart." Romans 4:12

As the seat of imagination:
In Mary's Magnificat, Luke 1:51,
"He has shown strength with His arm;
He has scattered the proud in the imagination of their heart."

As the seat of conscience:
After hearing Peter speak on the day of Pentecost Scripture says, "Now when they heard this, they were cut to the heart, and said to Peter and the rest of the apostles, 'Men and brethren, what shall we do?'"
Acts  2:37

As the seat of obedience:
"But thanks be to God that though you were slaves of sin, you became obedient from the heart to that form of teaching to which you were committed." Romans 6:17

As the seat of faith:
"That if you confess with your mouth Jesus as Lord, and believe in your heart that God raised Him from the dead, you shall be saved; For with the heart man believes, resulting in righteousness, and with the mouth he confesses, resulting in salvation." Romans 10:9-10

As the seat of purpose:
"Let each one do just as he has purposed in his heart; not grudgingly or under compulsion; for God loves a cheerful giver." 2 Corinthians 9:7

The heart is the center of our being and only God knows it fully. So we look to the indwelling Holy Spirit to open it up to us, that we may be all that our Heavenly Father intends for each of us to be here and now. And let us hold fast to the admonition of Proverbs 4:23 above.

With our whole hearts let us give all praise and glory to God. Amen