The parable of the leaven also known as the parable of the yeast is one of the shortest parables of Jesus, but very deep. Matt13:33, Luke12:20-21.
In this passage yeast is used as a positive symbol of growth. Although yeast looks like a minor ingredient, it permeates the whole loaf. Although the kingdom began small and was nearly invisible, it would soon grow and have a great impact on the world. Acts19:20.
“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.” Matt13:33, Luke 13:20.

“Another parable spake he unto them; In this chapter Matthew 13 there is nothing more significant than the sources from which Jesus drew His parables. In every case He drew them from the scenes and activities of everyday life. He began with things which were entirely familiar to His hearers in order to lead them to things which had never yet entered their minds. He took the parable of the sower from the farmer’s field Matt13:3, and the parable of the mustard seed from the husbandman’s garden; Matt13:31. He took the parable of the wheat and the tares from the perennial problem which confronts the farmer in his struggle with the weeds, Matt13:24, and the parable of the drag-net from the seashore of the Sea of Galilee. Matt13:47. He took the parable of the hidden treasure from the everyday task of digging in a field, Matt13:44, and the parable of the pearl of great price from the world of commerce and trade. Matt13:45-46. But in this parable of the leaven Jesus came nearer home than in any other because he took it from the kitchen of an ordinary house. which a woman took, and hid in three measures of meal.

In Palestine bread was baked at home; three measures of meal was, a just the average amount which would be needed for a baking for a fairly large family, like the family at Nazareth. Jesus took His parable of the Kingdom from something that He had often seen His mother, Mary, do. Three measures, signify a great abundance; that definite number standing for an indefinite quantity.
The kingdom of heaven is like unto leaven. Note here the wisdom of the Saviour; He first brings instances from nature, proving that as the one is possible so is the other. And He says not simply ‘put,’ but hid; as much as to say, So ye, when ye shall be cast down by your enemies, then ye shall overcome them. And so leaven is kneaded in, without being destroyed, but gradually changes all things into its own nature; so shall it come to pass with your preaching. Fear ye not then because I said that many tribulations shall come upon you, for so shall ye shineforth, and shall overcome them all. He says, three measures, to signify a great abundance; that definite number standing for an indefinite quantity.

which a woman took, and hid three measures of meal. the woman who takes the leaven and hides it, seems to be the Apostolic preaching, or the Church gathered out of diver’s nations. She takes the leaven, that is, the understanding of the Scriptures, and hides it in three measures of meal, that the three, spirit, soul, and body, may be brought into one, and may not differ among themselves. The woman is the Church, who has mingled the faith of man in three measures of meal, namely, belief in the Father, the Son, and the Holy Spirit; which when it has fermented into one lump, brings us not to a threefold God, but to the knowledge of one Divinity.
We are hidden from the evil one during our transition. The 3 - Father, son, and Holy spirit help to hide us, to feed us…until we have grown to our full potential and understanding in the Kingdom -- usually 3 1/2 years. At that time, we have risen in wisdom and faith and are ready to represent the Lord.
till the whole was leavened. He says, Until the whole was leavened, because that love implanted in our mind ought to grow until it changes the whole soul into its own perfection; which is begun here, but is completed hereafter.

He told them another parable. “The kingdom of heaven is like leaven that a woman took and hid in three measures of flour, till it was all leavened.” Matt13:33 (ESV) He told them still another parable: “The kingdom of heaven is like yeast that a woman took and mixed into about sixty pounds of flour until it worked all through the dough.” Matt13:33 (NIV)
What is a leaven? A leaven is a substance, typically yeast, that is used in dough or bread to make it rise.it only takes a little bit of yeast to leaven the bread i.e. to make the bread rise. Leaven is a raising agent. Leaven was a little piece of dough kept over from a previous baking, which had fermented in the keeping.

What dose a leaven signify? The leaven signifies love, because it causes activity and fermentation; by the woman He means wisdom. By the three measures He means those three things in man, with the whole heart, with the whole soul, with the whole mind; or the three degrees of fruitfulness, the hundred-fold, the sixty-fold, the thirty-fold, Matt13:8&23, or those three kinds of men, Noah, Daniel, and Job." POINT OF NOTE: In Jewish language and thought, leaven is almost always connected with an evil influence; the Jews connected fermentation with rottenness and leaven stood for that which is evil. Matthew 16:6 : 1 Corinthians 5:6-8 , Galatians 5:9 . One of the ceremonies of preparation for the Passover Feast was that every scrap of leaven had to be sought out from the house and burned. It is possible that Jesus chose this illustration of the Kingdom deliberately. It may be shocking to hear the Kingdom of God compared to leaven; and the shock may arouse interest and attract attention, just as illustrations from an unusual and unexpected source always does.

The whole point of the parable lies in one thing–the transforming power of the leaven. Leaven changed the character of a whole baking. Unleavened bread is like a water biscuit, hard, dry, unappetizing and uninteresting; bread baked with leaven is soft and porous and spongy, tasty and good to eat. The introduction of the leaven causes a transformation in the dough; and the coming of the Kingdom causes a transformation in life.

What are the characteristics of this transformation.?
(i)
Christianity transformed life for the individual man. In 1 Corinthians 6:9-10 , Paul gathers together a list of the most terrible and disgusting kinds of sinners, and then, in the next verse, there comes the tremendous statement: “And such were some of you.” we must never forget that the function and the power of Christ is to make bad men good. The transformation of Christianity begins in the individual life, for through Christ the victim of temptation can become the victor over it.

(ii)
Christianity transformed life for women. The Jew in his morning prayer thanked God that he had not made him a Gentile, a slave or a woman. “When he came home, there was no home life. His father was hardly ever in the house. His mother was a nonentity, living in the women’s apartments; he probably saw little of her.” In the eastern lands it was often possible to see a family on a journey. The father would be mounted on an ass; the mother would be walking, and probably bent beneath a burden. One demonstrable historical truth is that Christianity transformed life for women.1Peter3:5, Acts1:14, Acts5:14, Phil4:3.

(iii)
Christianity transformed life for the weak and the ill. In heathen life the weak and the ill were considered a nuisance. Christianity was the first faith to be interested in the broken things of life. Matt11:28

(iv)
Christianity transformed life for the aged. Like the weak, the aged were a nuisance. Christianity was the first faith to regard men as persons and not instruments capable of doing so much work. Zech8:4.

(v)
Christianity transformed life for the child. Luke18:16. In the immediate background of Christianity, the marriage relationship had broken down, and the home was in peril. Divorce was so common. In such circumstances children were a disaster; and the custom of simply exposing children to death was common. There is a well-known letter from a man who wrote to his wife: “If–good luck to you–you bear a child, if it is a boy, let it live; if it is a girl, throw it out.” In modem civilization life is almost around the child; in ancient civilization the child had a very good chance of dying before it had begun to live.
There is nothing in history that demonstrates the transforming power of Christianity and of Christ on the individual life and on the life of society like Christianity.

There is nothing in history that demonstrates the transforming power of Christianity and of Christ on the individual life and on the life of society like Christianity.The parable of the leaven speaks of the transforming power of Christ and of His Kingdom in the life of the individual and of the world; but how does this transforming power work?
(i)
The lesson of this parable is that the Kingdom works unseen. We cannot see the leaven working in the dough, any more than we can see a flower growing, but the work of the leaven
is always going on. Just so, it is
said, we cannot see the work of the Kingdom, but always the Kingdom is working and drawing men and the world ever nearer to God.This, then, would be a message of encouragement. It would mean that at all times we must take the long view, that we must not compare things of the present day with last week, month, or even last year, but that we must look back down the centuries, and then we will see the steady progress of the Kingdom.
(ii)
The parable teaches that with Jesus Christ and His gospel a new force has been let loose in the world, and that, silently but inevitably, that force is working for righteousness in the world and God indeed is working His purpose out as year succeeds to year.
(iii)
The lesson of the parable is that the working of the Kingdom can be plainly seen. The working of the leaven is plain for all to see. Put the leaven into the dough, and the leaven changes the dough from a passive lump into a seething, bubbling, heaving mass. Just so the working of the Kingdom is a violent and disturbing force plain for all to see. When Christianity came to Thessalonica the cry was: “These men who have turned the world upside down have come here also” Acts 17:6 . The action of Christianity is disruptive, disturbing, violent in its effect. There is undeniable truth there. It is true that men crucified Jesus Christ because he disturbed all their orthodox habits and conventions; again, and again it has been true that Christianity has been persecuted because it desired to take both men and society and remake them. It is abundantly true that there is nothing in this world so disturbing as Christianity; that is, in fact, the reason why so many people resent it and refuse it, and wish to eliminate it.When we come to think of it, we do not need to choose between these two views of the parable, because they are both true. There is a sense in which the Kingdom, the power of Christ, the Spirit of God, is always working, whether or not we see that work; and there is a sense in which it is plain to see. Many an individual life is manifestly and violently changed by Christ; and at the same time there is the silent operation of the purposes of God in the long road of history.
(iv)
This parable teaches both that the Kingdom is for ever working unseen, and that there are times in every individual life and in history when the work of the Kingdom is so obvious, and so manifestly powerful, that all can see it. Acts4:16.

CONCLUSION: Our Lord Jesus sets forth in this parable of the leaven before His disciples that, as leaven changes into its own kind so shall ye change the whole world. In other words, as the leaven could change to its own nature, the meal or dough with which it is mixed, so the nature of the grace of Christ is to change the whole soul into its own likeness; and God intends that this principle should continue in the soul till all is leavened-till the whole bear the image of the heavenly, as it before bore the image of the earthly. Both these parables are prophetic, and were intended to show, principally, how, from very small beginnings, the Gospel of Christ should pervade all the nations of the world, and fill them with righteousness and true holiness. Ask the Lord now: Lord, help me to grow spiritually and physically in power and holiness in the name of Jesus