Luke 13: 18 - 21
18 He said therefore, "What is the kingdom of God like? And to what shall I compare it?
19 It is like a grain of mustard seed which a man took and sowed in his garden; and it grew and became a tree, and the birds of the air made nests in its branches."
20 And again he said, "To what shall I compare the kingdom of God?
21 It is like leaven which a woman took and hid in three measures of flour, till it was all leavened."

EWTN