Peace be with you.
The heart is not the seed of motivation, it is the source of which all your emotions, desires, cravings (both good and bad) dwell. It is not your physical fleshly heart, but your spirit's heart. The desires of your flesh that have been "deeply embedded" by you in your spirit. The 'spirit' is the TRUE you without your outward appearance. It possesses all your true desires, both hidden and not hidden. When the Father JAH examines your heart, he is examining and seeing your truest motives, your truest desires in the most illicit form. He sees the desires openly in the most uncensored form. The Father, through his Son then elicits (draws out hidden things; brings to light deep things) these things from our hearts and shows them to us. He does this for our benefit that we may have the opportunity to submit these desires to hi and ask him by means of holy spirit to REMOVE these bad desires so that we can have a 'clean heart'and have no hidden wicked motives that will potentially harm someone.