Adam Clarke on Matthew 16:7

They reasoned - For, as Lightfoot observes, the term leaven was very rarely used among the Jews to signify doctrine, and therefore the disciples did not immediately apprehend his meaning. In what a lamentable state of blindness is the human mind? Bodily wants are perceived with the utmost readiness, and a supply is sought with all speed. But the necessities of the soul are rarely discovered, though they are more pressing than those of the body, and the supply of them of infinitely more importance.