Mat 13:33 Another parable spake he unto them; The kingdom of heaven is like unto leaven, which a woman took, and hid in three measures of meal, till the whole was leavened. – Jesus (Matthew 13:33)
Parables are like grapes, small contained packages bursting with flavor when you bite. They usually have one main point so Jesus sometimes told them in bunches.
Here Jesus tells his audience the Kingdom of Heaven is like yeast. Yeast is symbolical throughout the Bible of several things, some good and some bad, but here Jesus points to one thing it is noted for — its ability to permeate.
God’s Kingdom is infectious. This may be one reason Jesus leaves most of his people within their society. Put a believer, who really loves Jesus, inside a company or a family and the Kingdom eventually touches everyone. They may not all accept Christ but they won’t be the same — either he/she has to change or they do.
— fritz@langgang.com
Patrikin - Kinship through The Father 