Another parable spoke 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.
All Commentaries on Matthew 13:33 Go To Matthew 13
Hilary of Poitiers
AD 368
Many seem to believe that the three measures of flour refer not only to the sign of faith—that is, the unity of the Father and the Son and the Holy Spirit—but also to the calling of the three nations out of Shem, Ham and Japheth. But I do not know whether reason will permit us to draw this conclusion, for, although the calling of all nations is equal, Christ is not buried in them but manifested to them, and the whole batch is not fermented in so great a multitude of unbelievers. However, in the Father and the Son and the Holy Spirit, without the need of yeast applied from without, all things are one in Christ.