This is part two of the infamous (and badly named) three post night...
The second part of the Shema goes a little something like this: "You shall love YHWH your God with all your heart, with all your soul, and with all your strength..." Fairly standard. Good tripartite breakdown of the human 'person', eh? Well...maybe not.
Concentrate for a moment with me on the 'soul'. The Hebrew word is 'nephesh' (if I could get Hebrew fonts here, oh baby, you know I would), which means 'life, being, person, soul'. Unfortunately, many lexicons have omitted its base meaning: throat. It is understandable way, also, because it doesn't fit with Western metaphorical systems to say "Bless YHWH, o my throat, and all that is within me" or "My throat thirsts for the Living God". In fact, it sounds a little stilted in translation--but that is just because it is unused, think of how wooden and stilted the KJV can sound to us today, even though it was once the standard way to speak.
It is too much right now to get into the history of the 'Christian' (neoplatonic) soul. But, if we had the 'stones' (a Biblical euphemism) to translate it as throat, we might have a new anthropology arise out of the Biblical text. No longer would it be some tripartite metaphysical/psychological understanding, but a very earthy (creational) way of viewing the human person. But why nephesh in the Shema?
In Genesis 2, God takes the 'adamah' (soil), breathes the breath of life (ruah--the same word for Spirit/breath/wind), and the two combined make a living nephesh. The word of living, used in such contexts as 'living waters' and others, basically means moving--dead things don't move much of their own accord. So, in this passage, the human body is brought to life by God's Spirit and his throat starts letting breath in and out, he is living. Instead of saying that man has an immaterial 'soul', it is saying that human life is ultimately important and has great ramifications for the resurrection. The throat is where the signs of life are found, respiration and also various emotions (such as getting choked up with tears, having a lump in your throat, etc.). The word nephesh, as it progressed in the Bible, never lost this basic meaning, but also expanded to metaphorically mean 'the whole person' (see the NIV translation of the Genesis 2 passage).
So here is what we have: the heart is the seat of the intellect and will, the nephesh is the whole person, and the strength is the possessions/wealth of the person (see Anthony's sermon for this point). The nephesh, as the place where life comes from, where praise proceeds from, works as the prime spot where the sovereignty of YHWH should be totally expressed as a symbol for a whole life lived to God.