Jesus' disciples asked Him to explain this parable to them, and He said: "The field represents the world, and He that sowed the good seed is Christ Himself. The good seed is the Word He preached; the wheat plants are the good people who believe in Christ and do as He teaches. The enemy who sows the bad seed is Satan, and the tares that spring from them are wicked people who follow the promptings of the evil one in their hearts. The harvest is the end of the world, and the reapers are the angels of God. As therefore the tares are gathered and burned in the fire, so shall it be in the end of this world with wicked people. Christ shall send forth His angels, and they shall gather out of His Kingdom all things that offend and them that do evil, and shall cast them into a furnace of fire; there shall be wailing and gnashing of teeth. Then shall the righteous shine forth as the sun in the kingdom of their Father."
"For the Lord our God shall come, And shall take His harvest home; From His field shall in that day All offences purge away;
"Give His angels charge at last In the fire the tares to cast, But the fruitful grain to store In His garner evermore."
Christ said that the kingdom of heaven could be likened unto leaven (or yeast), which a woman took and hid in three measures of flour, till the whole was leavened.
Now, this leaven, or yeast, is composed of tiny little plants, each one so small that it cannot possibly be seen by the sharpest eye except through a very powerful microscope. So small are they that it would require three thousand of them, placed close together, side by side, to make up the length of one inch. Like all other plants they require food, and they find this in the dough they are placed in. You know that all things are made up of atoms of chemical substances so wonderfully blended together that only the chemist can separate them, and when he has separated them they appear very different. Well, in flour there are certain things so blended, and the yeast-plant takes one kind of substance as food, and in doing so sets free another substance called carbonic acid gas. This gas bubbles up and makes the heavy dough spongy and light. If it were not for these tiny bubbles of gas your bread would be as heavy and close as suet pudding. This is the reason why yeast is put into dough for making bread or cake. One of the most remarkable things about this yeast is, that when it gets into any substance that contains its food, it at once begins to give off buds, which, in a few moments, become full-sized and break away. So rapid is this increase, that if a single yeast-plant were to be put into a great mass of dough it would very quickly leaven the whole mass.