We all know what yeast does-- it gets dough "excited" and causes it to rise. Without yeast, or leaven, breads would all be flat, more like crackers than bread. They would be the flatbread that Jews eat at Passover. Jesus invokes the idea of yeast in today's Gospel (Lk 13: 18-21) when He uses the image of a woman who took yeast and mixed it into three measures of flour, until the whole batch was leavened. The woman did that so that all of the dough would rise properly into the bread she was making. Jesus compares that process to the Kingdom of God, where something which looks small, like yeast, can fundamentally change the results in something a whole lot larger. He uses the image of a mustard seed to the same effect-- something small which grows and blossoms into a large bush, big enough for a large flock of birds. Something small energizing, growing into, something very large-- that's what Jesus wants us to be thinking about in this couple of metaphors. So, what is it in our individual situation which is our "yeast"? What excites us about the Church and about Christ? What small thing motivates us, keeps us engaged, causes the Kingdom of God, which is within us, to grow? We might reflect on that because the answer to that set of questions might give us the key to how we are to get stronger in our faith. It is worth considering because we don't all react to the same "yeast." Some of us long for traditional liturgies; others find that style of worship pretentious and unfulfilling. Some like wonderful, professional music at church; others prefer to be part of a congregation that sings, unprofessional as it may be. The list goes on. One of the joys of the Catholic Church is that there is a huge variety of options when it comes to liturgy, or prayer groups, or Bible study, or men's clubs, or whatever. Think about what makes you expand, grow, blossom and participate in it. Maybe even consider being the "yeast" yourself, providing that energy, that excitement that your community needs. In some measure this is about change-- yeast changes the dough, making it do things it otherwise wouldn't do-- and change can be hard. But change can also be exciting and energizing. Change is the way of the world, and something all institutions need to address. How can you be "yeast" in your world, and thus grow the Kingdom of God?