13:18-22 Here is the progress of the gospel foretold in two parables, as in Mt 13. The kingdom of the Messiah is the kingdom of God. May grace grow in our hearts; may our faith and love grow exceedingly, so as to give undoubted evidence of their reality. May the example of God's saints be blessed to those among whom they live; and may his grace flow from heart to heart, until the little one becomes a thousand.See these parables explained in the notes at Matthew 13:31-32. Lu 13:18-30. Miscellaneous Teachings.

18-21. mustard seed … leaven—(See on [1657]Mr 4:30-32). The parable of "the Leaven" sets forth, perhaps, rather the inward growth of the kingdom, while "the Mustard Seed" seems to point chiefly to the outward. It being a woman's work to knead, it seems a refinement to say that "the woman" here represents the Church, as the instrument of depositing the leaven. Nor does it yield much satisfaction to understand the "three measures of meal" of that threefold division of our nature into "spirit, soul, and body," (alluded to in 1Th 5:23) or of the threefold partition of the world among the three sons of Noah (Ge 10:32), as some do. It yields more real satisfaction to see in this brief parable just the all-penetrating and assimilating quality of the Gospel, by virtue of which it will yet mould all institutions and tribes of men, and exhibit over the whole earth one "Kingdom of our Lord and of His Christ." (See on [1658]Re 11:15).

See Poole on "Luke 13:20"

And again he said,.... That is, Jesus, as the Syriac and Persic versions express it; besides the parable of the grain of mustard seed, that also of the leaven hid in three measures of meal:

whereunto shall I liken the kingdom of God; either the Gospel of the kingdom, and the mysteries of it; or the church, which is Christ's kingdom; or the grace of God in the heart, which makes meet for the kingdom of glory; the first seems rather to be intended; See Gill on Matthew 13:33.

And again he said, Whereunto shall I liken the kingdom of God?