"the Gospel miracles are ... acted parables of the kingdom." (FF Bruce)
The Parable of the Sower (Mark 4) describes grain multiplying many times over. It is followed by Jesus asking the disciples "Do you not understand this parable? How then will you understand all the parables?"
The Feeding of the Five Thousand (Mark 6) describes grain multiplying many times over. It is followed by an explanation that the disciple "did not understand [the acted parable] about the loaves, but their hearts were hardened".
The Feeding of the Four Thousand (Mark 8) describes grain multiplying many times over. It is followed by Jesus asking the disciples "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?".
Any thoughts?
