Matthew 13: 10 - 17
10 Then the disciples came and said to him, "Why do you speak to them in parables?"
11 And he answered them, "To you it has been given to know the secrets of the kingdom of heaven, but to them it has not been given.
12 For to him who has will more be given, and he will have abundance; but from him who has not, even what he has will be taken away.
13 This is why I speak to them in parables, because seeing they do not see, and hearing they do not hear, nor do they understand.
14 With them indeed is fulfilled the prophecy of Isaiah which says: `You shall indeed hear but never understand, and you shall indeed see but never perceive.
15 For this people's heart has grown dull, and their ears are heavy of hearing, and their eyes they have closed, lest they should perceive with their eyes, and hear with their ears, and understand with their heart, and turn for me to heal them.'
16 But blessed are your eyes, for they see, and your ears, for they hear.
17 Truly, I say to you, many prophets and righteous men longed to see what you see, and did not see it, and to hear what you hear, and did not hear it.

EWTN