I've also been confused by the emphasis placed on the different types of soils over against the seed, and how most sermons I've heard and preach emphasize the seed, when it seems that Jesus is emphasizing the soil.

But I think that Isaiah 6:9 really holds the key. It's from Isaiah's call narrative. In it God sends Isaiah to preach God's Word and pronounce His judgment over the His people because of their unrepentant sin.

And then Isaiah responds to his charge with this: "How long O Lord?" And the Lord replies:

“Until cities lie waste without inhabitant, and houses without people, and the land is a desolate

waste, and the Lord removes people far away, and the forsaken places are many in the midst of

the land. And though a tenth remain in it, it will be burned again, like a terebinth or an oak, whose

stump remains when it is felled.” The holy seed is its stump. (Is 6:11-13)

So the Israelites would be removed, exiled from the land by the Babylonians. The word that Isaiah was to proclaim was to harden the Israelites' hearts. To ensure that they didn't repent, and his judgment of exile be forestalled, so that God's holy seed could be the stump that remained in the land to provide abundant fruit for future generations.

The connection then is between seed and land. The seed that falls on the rocky, thorny, well-trodden soils is revealed by the seed to be what it is. The seed still works. It does what it was sent by God to do. To show its utter fruitlessness. The soil was surely this before the seed fell on it. But the seed confirms this judgment. It pronounces it. It does what it was supposed to do--so that seeing it doesn't see and hearing it doesn't understand. It shows that we are all still exiled from the good land. And thus we will not bear fruit.

But the good soil, too, is revealed by the seed. This soil is the good land in which the stump remains. This soil is the soil that has the holy seed planted in it. This is the promised seed of Eve, the one promised to Abraham, the one foreseen in Isaiah 55, that would come down and not return to the Father empty. This can be none other than Jesus Christ, the Word made flesh, who came down to water the earth with his blood, was planted into the earth, and returned to the Father with our recompense.

It seems that the Isaiah 6:9 quotation is there point us to the rest of Isaiah 6. To show us that we are all exiled from the good and fruitful land. That we are all unfruitful soil. And that we all have hope in the the stump that remains, the holy seed (offspring) of God.

Just some thoughts. What say you?