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.

322. In the spiritual sense bearing false witness means persuading others that false ideas of faith are true and that evil ways of life are good, and that true ideas are false and good ways are evil. But in both cases it means doing so deliberately, and not out of ignorance; that is, after knowing what truth and goodness are, but not before. For the Lord says:

If you were blind, you would not be committing a sin; but now you say, We see, therefore your sin remains, John 9:41.

This falsity is meant in the Word by 'lie' and this intention by 'deceit', in these passages:

We have struck an agreement with death, we have made a vision with hell. We have turned a lie into trust, and hidden ourselves behind a falsehood, Isaiah 28:15.

A rebellious people are they, lying sons who are unwilling to hear the law of Jehovah, Isaiah 30:9.

From prophet to priest, everyone acts a lie, Jeremiah 8:10.

The inhabitants utter a lie, and as for their tongue, deceit is in their mouth, Micah 6:12.

You will destroy those who utter a lie, Jehovah abominates the man of deceit, Psalms 5:6.

They taught their tongue to utter a lie; their dwelling is in the midst of deceit, Jeremiah 9:5-6.

It is because 'lie' means falsehood that the Lord says that the devil utters a lie of his own (John 8:44). 'A lie' also means falsity and untruth in these places: Jeremiah 23:14, 32; Ezekiel 13:6-9; 21:29; Hosea 7:1; 12:1; Nahum 3:1; Psalms 120:2-3.