"Blessed are the pure in heart, for they shall see God." Matthew 5:8

"Vine's Expository Dictionary of Old and New Testament Words"
defines KARDIA (the Greek word for heart): "the heart, the chief organ of the physical life, occupies the most important place in the human system.
By an easy transition the word came to stand for man's entire mental and moral activity, both the rational and emotional elements. In other words, the heart is used figuratively for the hidden springs of the personal life."

Proverbs 4:23 tells us,
"Above all else, guard your heart for it is the wellspring of life."

Vine quotes J. Laidlaw, in "Hastings' Bible Dictionary":
"The Bible describes human depravity as in the 'heart', because sin is a principle which has its seat in the centre of man's inward life, and then 'defiles' the whole circuit of his actions, ("For out of the heart proceed evil thoughts, murders, adulteries, fornications, thefts, false witness, blasphemies. These are the things which defile a man." Matthew 15:19-20)

The quote continues, "On the other hand, Scripture regards the heart as the sphere of Divine influence, ("So God, who knows the heart, acknowledged them, by giving them the Holy Spirit just as He did us, and made no distinction between us and them purifying their hearts by faith."
Acts 15:8-9)."  End of quote.

Scripture describes the heart of the regenerate. And who is he/she? Those who are born again; born of the Spirit.
"Not by works of righteousness which we have done, but according to His mercy He saved us, through the washing of regeneration and renewing of the Holy Spirit." Titus 3:5

We see that the heart of the regenerate is:
Contrite:
"The sacrifices of God are a broken spirit, A broken and a contrite heart -- These, O God, You will not despise." Psalm 51:17

Enlightened:
"For it is the God who commanded light to shine out of darkness who has shone in our hearts to give the light of the knowledge of the glory of God in the face of Jesus Christ." 2 Corinthians 4:6

A meditating one:
"Be angry, and do not sin.
Meditate within your heart on your bed, and be still..." Psalm 4:4

Pure:
Along with our opening verse David tells us in Psalm 73:1, "Truly God is good to Israel, To such as are pure in heart."

Prayerful:
1 Samuel 1:12-13 tells us of Hannah praying from her heart, "And it happened, as she continued praying before the Lord, that Eli watched her mouth, now Hannah spoke in her heart; only her lips moved, but her voice was not heard..."

Glad and sincere:
"Now all who believed were together, and had all things in common...so continuing daily with one accord in the temple, and breaking bread from house to house, they ate their food with gladness and simplicity of heart."
Acts 2:44 & 46

Steadfast:
"My heart is steadfast, O God, my heart is steadfast; I will sing and give praise." Psalm 57:7

Tender:
"'Because your heart was tender, and you humbled yourself before the Lord when you heard what I spoke...I also have heard you.' Says the Lord."
2 Kings 22:19

A treasury of good:
Jesus is speaking to the Pharisees who have blasphemed the Holy Spirit, "A good man out of the good treasure of his heart brings forth good things, and an evil man out of the evil treasure brings forth evil things."
Read the whole scenario Vs 22-37

Wise:
"The wise in heart will receive commands, But a prating fool will fall." Proverbs 10:8

Let us each look to our own hearts and be ever mindful of the admonition in Proverbs 4:23 above, to guard our hearts for it is the wellspring of life -- mind, emotions and will. As Believers we submit ourselves to the control of the Holy Spirit who leads and guides us into all truth. For He will reveal our hearts to us that we may be cleansed from any rebellion, unrighteousness, pride, fear, doubt, evil that lurks deep within. For we do not know the depths of our own hearts, but He does! Remember we are works in progress

Even so, Lord, have Your perfect way in our lives! Amen