If you were a first-century Palestinian peasant and you heard this craftsman-turned-prophet from Nazareth speak about the sower who went out to sow and got those mixed results (some seed lost to birds, some to sunburn, some to encroaching weeds, and finally some seed finding good ground and sprouting), how would you know you are supposed to hear this as a parable—a story that presents an image of something else? Maybe the man in the boat is just talking about how tough it is to farm in the stony, weedy, bird-bedeviled Palestinian soil. Would your response be, maybe, “Yup, that's agriculture”? If you were alert and soil-smart, you might pick up on at least two cues hinting that the story points beyond itself. First, the seed falling on the good soil produces a surprisingly abundant harvest: whereas the usual yield is ten seeds up for every one seed down, these seeds give 100, 60, and 30 seeds for every single seed put down. As an experienced farmer, you would notice this amazing contrast between the unpromising beginnings (seed squelched by birds, sun, and weeds) and the fantastic harvest that eventually emerges.
Second, you would likely have picked up on Jesus' saying, “Whoever has ears to hear ought to hear.” What's to hear? It must be a meaning beyond the obvious. Taking your lead from the talk of seed that achieves, willy-nilly, a successful harvest, and searching for the symbolic possibilities of that imagery, you just might recall the passage from Isaiah 55, this Sunday's First Reading. There the prophet compares the effectiveness of God's word with the natural processes of rain and snow nurturing the growth and fruitfulness of seeds.
The disciples may or may not have caught all this. As Matthew tells it, when they ask Jesus about the parable, he supplies another text from Isaiah (Isa 6:9-10) to explain what was hindering a fuller reception of his word—gross hearts, and ears and eyes that are spiritually deaf and blind.
Then Jesus proceeds to spell out an allegorical interpretation that names what blocks full growth of the word—failing to understand what was sown in the heart, being shallow in one's response and therefore wilting in the face of persecution, and being distracted by worldly anxiety and desire for riches.
That is all clear enough, but what sometimes confuses careful readers is the apparent confusion about what the seed represents. Matthew 13:19 seems to say that the seed is both “the word of the kingdom” and the person who responds (poorly or well). As the explanation continues, the emphasis is on the seed as person: e.g., “The seed sown on the rocky ground is the one who hears the word and receives it at once with joy” (Mt 13:20). We might like a clear equation, either seed = the word, or seed = person. But the biblical tradition gives precedent for seed symbolizing both of those meanings. Isaiah 55 associates seed with the word of God, but Hosea 2:23 and Jeremiah 31:27 use the sowing image for a renewed people.
So there is reason to make seed serve as a double-duty symbol. Indeed, Matthew, in the scene immediately preceding this parable's discourse, has provided an episode illustrating how a community of people is created by their response to the word of God. When Jesus is told that his mother and brothers are standing outside asking to speak with him, Jesus stretches out his hand toward his disciples, and says, “Here are my mother and my brothers. For whoever does the will of my heavenly Father is my brother, and sister, and mother” (Mt 12:49-50).