Jesus may have been giving his disciples a reality check when he told them the parable of the sower: All the seeds are good, but the ground really can differ.
Isaiah's message focuses on the positive. God sends rain to the earth and the rain returns to heaven. But, before returning, that rain causes seeds to sprout. Isaiah relates God's promise: "As the rain accomplishes my purpose, so does my word."
Isaiah is speaking to exiles fearing their homecoming.
When is it appropriate for us to remember the need for good soil? When is it appropriate for us to remember Isaiah's words of joy and welcome and inevitable love?