Charles Ellicott Commentary Luke 13:18-21

"He said therefore, Unto what is the kingdom of God like? and whereunto shall I liken it? It is like unto a grain of mustard seed, which a man took, and cast into his own garden; and it grew, and became a tree; and the birds of the heaven lodged in the branches thereof. And again he said, Whereunto shall I liken the kingdom of God? It is like unto leaven, which a woman took and hid in three measures of meal, till it was all leavened." — Luke 13:18-21 (ASV)

Then said he, Unto what is the kingdom of God like?—See Notes on Matthew 13:31-33. The first impression with most readers, in the absence of any apparent trace of sequence, is that we have an isolated fragment of our Lord’s teaching, torn from the context in which we find it in Matthew.

On the other hand, we must remember:

1. that our Lord was in the synagogue on the Sabbath day, so both time and place called for teaching of some kind;
2. that the parables that follow may well be regarded simply as samples of the teaching which those who were in the synagogue had treasured in their memories.

They were suitable and edifying parables at any time; not least, assuredly, at this particular time.

When proof had been given that the Kingdom of God had indeed come near to people, it was good to set before them something about its nature, its extent, and its mode of working inwardly and outwardly. Moreover, the fact that these similitudes, which accomplished this, had been used before did not necessarily make them inapplicable or unprofitable when used again.