As the mental center, the heart knows, understands, reflects, considers, and remembers.

Know then in your heart that as a man disciplines his son, so the LORD your God disciplines you. (Deuteronomy 8:5)

So give your servant a discerning heart to govern your people and to distinguish between right and wrong. For who is able to govern this great people of yours? (1 Kings 3:9)

God gave Solomon wisdom and very great insight, and a breadth of understanding as measureless as the sand on the seashore. (I Kings 4:29)

As the emotional center, it is the seat of joy, courage, pain, anxiety, despair, sorrow, love, and fear.

Love the LORD your God with all your heart and with all your soul and with all your strength. (Deuteronomy 6:5)

Then the LORD's anger burned against Moses and he said, "What about your brother, Aaron the Levite? I know he can speak well. He is already on his way to meet you, and his heart will be glad when he sees you." (Exodus 4:14)

Then Hannah prayed and said: "My heart rejoices in the LORD; in the LORD my horn is lifted high. My mouth boasts over my enemies, for I delight in your deliverance." (1 Samuel 2:1)

As the moral center, God tries the heart, sees the heart, refines the heart, searches the heart.

The crucible for silver and the furnace for gold, but the LORD tests the heart. (Proverbs 17:3)

All a man's ways seem right to him, but the LORD weighs the heart. (Proverbs 21:2)

I the LORD search the heart and examine the mind, to reward a man according to his conduct, according to what his deeds deserve. (Jeremiah. 17:10)