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.

407. Verses 15 Revelation 6:15-17. And the kings of the earth, and the great ones, and the rich, and the commanders of thousands, and the mighty, and every servant, and every freeman, hid themselves in caves, and in the rocks of the mountains. And they said to the mountains and to the rocks, Fall on us, and hide us from the face of Him that sitteth on the throne, and from the anger of the Lamb. For the great day of His anger is come, and who is able to stand? 15. "And the kings of the earth, and the great ones, and the rich, and the commanders of thousands, and the mighty," signifies all internal goods and truths, and all external goods and truths, by means of which there are wisdom and intelligence n. 408; "and every servant and every freeman" signifies the natural man and the spiritual man n. 409; "hid themselves in caves, and in the rocks of the mountains," signifies truths and goods destroyed by evils of life, and by falsities therefrom n. 410.

16. "And they said to the mountains and rocks, Fall on us," signifies to be covered over by evils and by falsities therefrom n. 411; "and hide us from the face of Him that sitteth on the throne, and from the anger of the Lamb," signifies lest they should suffer direful things from the influx of Divine good united to Divine truth proceeding from the Lord. n. 412).

17. "For the great day of His anger is come," signifies the Last Judgment upon the evil n. 413; "and who is able to stand?" signifies who shall live and bear it? (n. 414).