Luke 13:19
It is like a grain of mustard seed, which a man took, and cast into his garden; and it grew, and waxed a great tree; and the fowls of the air lodged in the branches of it. It is like a grain of mustard seed, which a man took, and cast into his garden; and it grew, and waxed a great tree; and the fowls of the air lodged in the branches of it.
The kingdom is like a grain of mustard seed cast into a garden, beginning humbly and appearing insignificant like a tiny seed, then growing into a great tree where the birds lodge in its branches, spreading its influence widely and enduring after earthly kingdoms have perished. It was given during a traveling teaching ministry as the example of the work followers are to take up, showing their need for the baptism of the Holy Spirit, and it comes from the Sovereign of heaven. The same laws that govern earthly sowing and reaping govern the sowing of the seeds of truth, with the gospel seed growing by unseen divine life and agency rather than by human power or force.
The simple, brief words of divine truth are the seed that takes root in the hearer and bears fruit through the life-giving power of the Spirit, showing that the work and its power belong to Christ rather than to the human messenger. The gospel itself is a mystery hidden for ages that human wisdom cannot sound by trying to fathom its depths, and the Word in gospel sowing is to be communicated as truth and interwoven with the whole practical life. The pattern repeats in every generation, where a special truth and work begin with few advocates who may be opposed and despised by powerful religious and worldly authorities yet the work grows, applying both to the small beginnings of the gospel and to those who carry its message including reformers and missionaries.
The little seed becoming a tree reaches a signal and triumphant fulfilment in the last generation when the last message of warning and mercy goes to every nation and kindred and tongue to take out a people for His name and the earth is lightened with His glory. The work of truth beginning small grows large and flourishing when moved under the orders of Christ and by united effort with an established system of organization, developing from a small beginning into a great work. The great tree means the spread of truth, the multiplication of institutions, the carrying forward of missionary enterprises such as schools and health institutions, and the success of the system of organization sustained by systematic benevolence according to Bible plans.