No one can deny, without doing great violence to our Lord's words as recorded in Matt. iii. 10-15; Mark iv. 11, 12; Luke viii. 9, 10, that it was sometimes his purpose in teaching by parables, to withdraw from certain of his hearers the knowledge of truths which they were unworthy or unfit to receive. If not, where would be the fulfilment of the prophecy in Isaiah vi. 10? It is not that by the command, "Make the heart of this people fat," we need understand that any peculiar hardening passed upon them, but that the Lord having constituted as the righteous law of his moral government, that sin should produce moral insensibility, declared that he would allow the law in their case to take its course. The fearful curse of sin is, that it has ever the tendency to reproduce itself, that he who sows in sin reaps in spiritual darkness, which delivers him over again to worse sin.
- from page 7, Notes on the Parables of Our Lord