5 But this parable He speaks, as anointing His disciples, and to teach them, that even though the lost be more than such as receive the word yet they are not to despond. For this was the ease even with their Lord, and He who fully foreknew that these things should be, did not desist from sowing.
And how can it be reasonable, says one, to sow among the thorns, on the rock, on the wayside? With regard to the seeds and the earth it cannot be reasonable; but in the case of men's souls and their instructions, it has its praise, and that abundantly. For the husbandman indeed would reasonably be blamed for doing this; it being impossible for the rock to become earth, or the wayside not to be a wayside, or the thorns, thorns; but in the things that have reason it is not so. There is such a thing as the rock changing, and becoming rich land; and the wayside being no longer trampled on, nor lying open to all that pass by, but that it may be a fertile field; and the thorns may be destroyed, and the seed enjoy full security. For had it been impossible, this Sower would not have sown. And if the change did not take place in all, this is no fault of the Sower, but of them who are unwilling to be changed: He having done His part: and if they betrayed what they received of Him, He is blameless, the exhibitor of such love to man.
But do thou mark this, I pray you; that the way of destruction is not one only, but there are differing ones, and wide apart from one another. For they that are like the wayside are the coarse-minded, and indifferent, and careless; but those on the rock such as fail from weakness only.
For “that which is sown upon the stony places,” says He, “the same is he that hears the word, and anon with joy receives it. Yet has he not root in himself, but endures for a while; but when tribulation or persecution arises because of the word, by and by he is offended! When any one,” so He says, “hears the word of truth and understands it not, then comes the wicked one, and catches that which was sown out of his heart. This is he that is sown by the wayside.”
Now it is not the same thing for the doctrine to wither away, when no man is evil entreating, or disturbing its foundations, as when temptations press upon one. But they that are likened to the thorns, are much more inexcusable than these.
Source: Homilies on the Gospel of St. Matthew (New Advent)