Both of the settings in today's Gospel passage — one about a man gardening and the other about a woman baking — compare the initial smallness of an object to the considerable impact it goes on to have. A tiny mustard seed grows into a gigantic tree, which provides a home for the birds of the air. A little bit of yeast transforms a small amount of flour into a large amount of bread.
As images of God's kingdom, Jesus seems to be saying that in God's sight, what is very small can become highly significant. Even our most minor acts of kindness can result in good beyond anything we can imagine. Small acts of kindness, mercy, and acceptance, performed in the service of the LORD, can create an opportunity for the LORD's grace to work quite powerfully in our lives.
We might be tempted to think that unless some event within the Church is great and extraordinary, it does not matter much. However, today's gospel passage suggests that it is often the small actions, the little endeavors, that often go overlooked by most people that can become the heralds of the kingdom of heaven.