This parable is recorded by St. Mark alone. It differs greatly from the parable of the sower, although both of them are founded upon the imagery of the seed cast into the ground. In both cases the seed represents the doctrine of the gospel; the field represents the hearers; the harvest the end of the world, or perhaps the death of each individual hearer.
So is the kingdom of God, in its progress from its establishment to its completion. The sower casts seed upon the earth, not without careful preparation of the soil, but without further sowing. And then he pursues his ordinary business.
He sleeps by night; he rises by day; he has leisure for other employment; his work as a sower is finished. Meanwhile the seed germinates and grows by its own hidden virtues, assisted by the earth, the sun, and the air, the sower knowing nothing of the mysterious process.
First comes the blade, then the ear, then the full corn in the ear. Such is the preaching of the gospel. Here, therefore, the sower represents human responsibility in the work. The vitality of the seed is independent of his labour.
The earth develops the plant from the seed by those natural but mysterious processes through which the Creator is ever working. So in spiritual things, the sower commences the work, and the grace of God perfects it in the heart which receives these influences.
The earth beareth fruit of herself. In like manner, by degrees, the faith of Christ increases through the preaching of the gospel; and the Church grows and expands. And what is true of the Church collectively is true also of each individual member of the Church.
For the heart of each faithful Christian produces first the blade, when it conceives good desires and begins to put them into action; then the ear, when it brings them to good effect; and lastly the full corn in the ear, when it brings them to their full maturity and perfection.
Hence our Lord in this parable intimates that they who labour for the conversion of souls ought, with much patience, to wait for the fruit of 'their labour, as the husbandman waits with much patience for the precious fruits of the earth.