Yeast

A critical theme in the Gospel of Mark is the coming of the kingdom of God (note Jesus first words in this book [Mark 1:15]). The language in Mark 8:18 ("Having eyes, do you not see? And having ears, do you not hear?") relates to the idea of the kingdom of God for three main reasons:

1. It is a quote from Ezekiel 12:2, a passage in which God threatens to exile his people from the land -- the very exile from which the Jews in Jesus' day were waiting to be restored. This restoration from exile was the restoration of the kingdom of God. Ezekiel's audience was eventually exiled because having eyes, they did not see, and having ears, they did not hear. Jesus' miracles demonstrated that he was restoring the kingdom of God, and he was surprised that his disciples had failed to grasp the truth and/or significance of this.

2. The quote from Ezekiel 12:2 recalls Jesus earlier quote (Mark 4:12) from Isaiah 6:9-10: "While seeing, they may see and not perceive; and while hearing, they may hear and not understand lest they return and be forgiven." The context of the earlier quote is explicitly Jesus' teaching about the kingdom of God (Mark 4:11). Mark used this theme to return his readers' minds to the idea of the kingdom of God.

3. Jesus concludes this whole chapter of teaching with a direct referrence to the kingdom of God (Mark 9:1). By summarizing his teaching in Mark 8 by asserting that he was in fact restoring the kingdom of God, he indicated that restoring the kingdom of God had been the subject of Mark 8.

In Mark 8:11-12, the Pharisees challenged Jesus by deminading signs. Jesus responded by saying that he would not give them any signs. Of course, already given many signs, and he continued to do provide signs sufficient to demonstrate that he was the Christ and that he was restoring the kingdom of God (Mark 8 18-21). His point with the Pharisees was not that he would do no miracles during his ministry, but that he would not provide sufficient signs to those who did not deserve them (compare Mark 4:11-12), i.e. those who rejected Christ and the kingdom he offered.

"Yeast" or "leaven" is something that permeates and affects something else (compare 1 Cor. 5:6). When Jesus warned against the "yeast" or "leaven" of the Pharisees, he was warning his disciples not fall into the mindset of the Pharisees and Herod. Herod is signficant because he does not otherwise appear in this context. The only other place in which Mark refers to him is Mark 6, in which Herod also spoke of a kingdom (Mark 6:23) -- the kingdom he ruled under Roman domination. The Pharisees and Herod were too focused on their own earthly advantage to see that the kingdom Jesus offered was the real kingdom of God -- they preferred the earthly kingdom of bondage. Peter explicitly had a similar problem in this chapter (Mark 8:33), and all the disciples were in danger of falling into this way of thinking. The disciples needed to hear Jesus' warning.

The "yeast" or "leaven" metaphor was particularly poignant in that leaven was used in the baking of bread, something Jesus had just miraculously provided on two occasions (Mark 8:19-20). Metaphorically, Jesus was implying that the disciples should not set as their goals the things that the Pharisees and Herod valued (man's interests; Mark 8:33). Rather, they were to do and think as Jesus taught them, according to God's interests (Mark 8:33).