The first 23 verses of the Book of Matthew, chapter 13, record the Lord Jesus’s parable of the sower, His reasoning behind speaking in parables, and His explanation of the sower parable. This is His explanation:
“Hear then the parable of the sower:
When anyone hears the word of the kingdom and does not understand it, the evil one comes and snatches away what has been sown in his heart. This is what was sown along the path.
As for what was sown on rocky ground, this is the one who hears the word and immediately receives it with joy, yet he has no root in himself, but endures for a while, and when tribulation or persecution arises on account of the word, immediately he falls away.
As for what was sown among thorns, this is the one who hears the word, but the cares of the world and the deceitfulness of riches choke the word, and it proves unfruitful.
As for what was sown on good soil, this is the one who hears the word and understands it. He indeed bears fruit and yields, in one case a hundredfold, in another sixty, and in another thirty.”
Matthew 13:18-23 English Standard Version (ESV)
John Calvin comments on the parable as a whole:
…He only intended to warn us, that, in many persons, the seed of life is lost on account of various defects, in consequence of which it is either destroyed immediately, or it withers, or it gradually degenerates.
That we may derive the greater advantage from this warning, we ought to bear in mind, that he makes no mention of despisers who openly reject the word of God, but describes those only in whom there is some appearance of docility.
But if the greater part of such men perishes, what shall become of the rest of the world, by whom the doctrine of salvation is openly rejected?
And relative to the good soil:
But he that received the seed into a good soil… None are compared by Christ to a good and fertile soil, but those in whom the word of God not only strikes its roots deep and solid, but overcomes every obstacle that would prevent it from yielding fruit.
Is it objected that it is impossible to find anyone who is pure and free from thorns? It is easy to reply, that Christ does not now speak of the perfection of faith, but only points out those in whom the word of God yields fruit. Though the produce may not be great, yet everyone who does not fall off from the sincere worship of God is reckoned a good and fertile soil…
…Hence too we learn that we have no right to despise those who occupy a lower degree of excellence; for the master of the house himself, though he gives to one the preference above another on account of more abundant produce, yet bestows the general designation, good, even on inferior soils…
…Put away all filthiness and rampant wickedness and receive with meekness the implanted word, which is able to save your souls. James 1:21 (ESV)