What is the precise meaning of soul, mind, and heart in the greatest commandment?

Man is made of two components, body and spirit, and 'spirit' and 'soul' can be used interchangeably. At death the body goes into the grave and the spirit or soul goes to heaven, hell, or purgatory. So why does Jesus say heart, soul, mind, and strength? Each word focuses on a different dimension. 'Heart' is the word we use for the center, the core, the essence, which you can picture as the fusion of the body and the spirit; in the middle of that joining is the heart. 'Mind' is a similar word, focusing on the conscious existence that thinks, which is why heart and mind can overlap. 'Strength' comes from the spirit controlling the body to do good works. 'Soul' itself is sometimes used of the body and sometimes of the spirit in the New Testament, because it names the whole entity produced by the fusion of the two. Jesus piles up all these terms because His message is that you must give Him everything you are, right down to the core; He does not want a lukewarm, halfhearted Christian, but a hundred percent, or He will spew you out.