Matthew 13:15

15. For this people’s heart is waxed gross The reason is now given why those withholdings of truth are inflicted. The minds of the people had grown too gross to receive it. For instance, had the parable of the mustard seed been explained to the Pharisees as indicating that the Gospel would yet fill the earth, it would only have excited their additional hostility, and hastened their purpose of accusing him as intending to subvert the existing government. As their purpose had become too fixed, and their hearts too hard to enter into the spirit and plan of the kingdom of God, its teachings must remain mysteries to them. Dull of hearing That is, of hearing what was most deeply essential to their good. Their eyes they have closed It is they who have done it. Their blindness is wilful. They close their own eyes to the beauty of the Gospel, and therefore its real principles must be kept from them. I should heal them As I would gladly do, if they would but allow it to be done.

It is the law of God’s spiritual kingdom, that resistance to truth hardens the heart. To brace their minds against the truth and to defend themselves in opposition to it, they arm themselves with countless falsehoods. Their minds thereby get into that state that it benefits them not; nay, even damages and condemns them. It may be then even a mercy to withhold it from them. They may use it to evil purposes, and it may bring them into greater sin. Or they may have so insulted it that they have by their own heinous guilt rendered themselves, like the damned in hell, unworthy of it.