And answering, they say to Jesus: We do not know. And Jesus, responding, said to them: Neither do I tell you by what authority I do these things. I do not tell you what I know, because you do not want to admit what you know. Most justly rejected, they indeed went away confused. And it was fulfilled what in the psalm the Father God says through the prophet: I have prepared a lamp for my Christ, that is, John himself. I will clothe his enemies with shame (Psalm 131). It should be noted, moreover, that the knowledge of the truth is to be hidden from those who seek it for two main reasons. Namely, when he who asks is either less capable of understanding what he seeks, or is unworthy because of hatred or contempt of the truth itself, to whom it ought to be revealed what he seeks. For one of these reasons, the Lord said: I still have many things to say to you, but you cannot bear them now. For the other reason, he commanded the disciples: Do not give what is holy to dogs, nor throw your pearls before swine.
Source: On the Gospel of Mark