Being aware of it, Jesus said to them, "Why do you discuss the fact that you have no bread? Do you not yet perceive or understand? Are your hearts hardened? Having eyes do you not see, and having ears do you not hear? And do you not remember? When I broke the five loaves for the five thousand, how many baskets full of broken pieces did you take up?" They said to him, "Twelve."read more.
"And when I broke the seven for the four thousand, how many large baskets full of pieces did you take up?" And they said, "Seven." He said to them, "Do you not yet understand?"

"You stiff-necked people, uncircumcised in heart and ears, you always resist the Holy Spirit. You are doing just as your fathers did.

But of Israel he says, "All day long I have held out my hands to a disobedient and contrary people."

About this we have much to say which is hard to explain, since you have become dull of hearing. For though by this time you ought to be teachers, you need someone to teach you again the first principles of God's word. You need milk, not solid food; for every one who lives on milk is unskilled in the word of righteousness, for he is a babe.read more.
But solid food is for the mature, for those who have their sense trained by practice to distinguish good from evil.