Paul uses three metaphors in chapter 3 of First Corinthians: physical development to represent spiritual growth and the growth of the Church as farming a field or constructing a building. Here are some observations on the latter two metaphors — first separately and then jointly.

Church as Field
The Corinthians did not understand that God deserves the glory, not man. Making things grow is so much more difficult than just planting or watering.

Church as Building
Paul writes “Let each one take care how he builds upon it [foundation of Jesus Christ].” We will sometimes build with the wrong “stuff.” It is not always obvious to us what is the best way to build the Church.

General Observations
In both metaphors, there is a reward, but it is given in the future, not in the present. It is also given by God, not by man. Also, farming and construction both require multiple participants due to the amount of work and the different skills required (especially with construction). In both metaphors, Paul begins the work — planting the seed and laying the foundation — while others continue the work. One person doing all the work is not the ideal.