Verse 21. - How is it that ye do not understand? A better reading here is οὔπω instead of πῶς οὐ. Therefore the words should run, Do ye not yet understand? It is as though our Lord said, "You ought to have perceived, both from my words and from my actions, that I was not speaking concerning earthly leaven or earthly bread, but concerning spiritual doctrine." St. Matthew here (Matthew 16:12) is careful to tell us that this reproof of Christ quickened their intellects, and forced them to understand.

8:11-21 Obstinate unbelief will have something to say, though ever so unreasonable. Christ refused to answer their demand. If they will not be convinced, they shall not. Alas! what cause we have to lament for those around us, who destroy themselves and others by their perverse and obstinate unbelief, and enmity to the gospel! When we forget the works of God, and distrust him, we should chide ourselves severely, as Christ here reproves his disciples. How is it that we so often mistake his meaning, disregard his warnings, and distrust his providence?And he said unto them,.... Since this was the case, and they so well remembered the miracles he had wrought, and the circumstances of them:

how is it that ye do not understand? my words concerning the leaven of the Pharisees, of the Sadducees, and of Herod, as to imagine I spoke of bread, taken in a literal sense; or that I concerned myself about the scantiness of your provisions, when you, might have learnt from my late miracles, how able I am to support you, if you had not so much as one loaf with you: wherefore it argues great want both of understanding and faith, and shows great stupidity, ignorance, and unbelief, to give such a sense of my words, and to be anxiously concerned on the score of your provisions.