44. Once people realize that “David” means the Lord, they can know why David so often wrote about the Lord in his psalms when he was writing about himself. See Psalm 89, for example, where we find,

I have made a covenant with my chosen one, I have sworn to David my servant, “I will establish your seed even to eternity and build your throne for generation after generation. And the heavens will bear witness to your wondrous work, and to [your] truth, in the congregation of the saints.” Then you spoke to your holy one in a vision and said, “I have put [ability to] help in a mighty one; I have raised up a chosen one from among the people. I have found David, my servant; I have anointed him with my holy oil. With him my hand will be strong; my arm will strengthen him also. My truth and my mercy will be with him, and his horn will be exalted in my name. And I will place his hand on the sea and his right hand on the rivers. He will cry out to me, ‘You are my Father, my God, and the Rock of my salvation.’ I will also make him the firstborn, high above the monarchs of the earth. My covenant will be established with him. I will make his seed endure to eternity and his throne as the days of the heavens. I have sworn once by my holiness; I will not lie to David. His seed will endure forever and his throne will be like the sun before me; it will be as established as the moon to eternity and a faithful witness in the clouds.” (Psalms 89:3-5, 19-21, 24-29, 35-37)

There is similar material in other psalms, such as Psalm 45:2-17, Psalm 122:4-5, and Psalm 132:8-18.

The heart means love. A good heart means love to the Lord and to the neighbor, while a hard or stony heart means the love of self or the world -- riches and things. When the psalmist asks the Lord to search his heart, he wants the Lord to see what it is that he loves. And we are what we love. What we eat may form our earthly body, but it's only temporary, what we love forms our spiritual body, beautiful or ugly as we have chosen. It's interesting to note that the first multi-cellular motion of our embryo is the pulsating that starts in a twist of blood vessel that is to become our heart, and the last motion of our natural body is our heartbeat. It is there for all of our natural life. And of course there is a beating heart in our spiritual bodies when we come to put them on.