Mark 4:12

That seeing they may see, &c. In punishment of their wilfully shutting their eyes, (Matthew xiii. 15.) God justly withdrew those lights and graces which otherwise he would have given them, for their effectual conversion. (Challoner) --- these speeches here and elsewhere, we are not to understand as if the spoke in parables to this end that the hearers might not understand, lest they should be converted; but we must learn the true sense from the corresponding texts in Matthew xiii, and Acts xxviii, where our Saviour and St. Paul render it thus: with their ears they have been dull of hearing, and their eyes they have shut. lest, perhaps, they may see, and understand, and be converted, and I heal them. Whereby it is evident, that the speaking in parables was not the cause, (for many besides the apostles heard and understood) but themselves, who would not hear and understand, and be converted: and thus they were the real cause of they own wilful and obstinate infidelity. And therefore also he spoke in parables, because they were not worthy to understand, as the others were to whom he expounded them. (Bristow)