The Parable of the Mustard Seed and Yeast
Mathew 13:31-34 explains these two parables in depth. The first one is of man who went to the field and sowed a mustard seed which was the least in size of all seeds. It later grew and became a big tree where birds came to nestle. The other one is of a woman who hid leaven in three measures of meal till the whole was leavened. This is how Jesus taught. When he was alone with his disciples, he would explain to them.
These two parables all have the same meaning. The seed is the word of God. The farmer is Jesus Christ. When he came to preach the gospel, he started at his home town Galilee and the gospel spread to the entire world since then. The gospel has been nourishing people and giving them a life and hope through the Savior Jesus. It started small, with one man, but it was and will spread to every corner of the world.
Our duty as Christians is to make this possible. This is by supporting those who preach the word to the nations and also doing it ourselves. We are all called to be ministers in the Kingdom of God in one way all another. Learn how and where God wants you to minister and you will win souls to God. Spreading the Gospel is the number one most important thing to God. For it, he allowed his Son to die so as you and I might get to know him and know his word too. Give someone else who does not yet know the word as you do a chance today.