Mark 4:27-28 are part of a parable depicting the mysteries of growth. In the farm world, a single kernel of corn germinates, grows up into a tall stalk, which typically has one or two ears; each ear has between 800 and 1200 kernels. Wow! That’s quite a return!
No less amazing is the work of the Holy Spirit in the human heart (the ground). When a person is converted, the Holy Spirit begins a transforming progress that occurs as the Lord Jesus Christ described it in this passage.
First, when the seed germinates, life begins; there is a change, but an outsider cannot see it. So, too, when one is saved, there is a change; there is new life, but it may not be apparent to others.
Second, the “blade” appears relatively soon. It is a small thing, but it is evidence of growth. Similarly, with the Holy Spirit of God residing with the person, there is some change that others can see. It may be a small thing, but it is something. Generally, blades may not be noticed by the casual observer, but one looking for it can spot it.
Third, the “ear” occurs – this is evidence of more to come; the plant is well beyond the “blade” stage. This stage is pretty well evident to everyone. So, too, in the believer’s life; the believer has grown quite a bit, and the change is noticeable.
Finally, there is is the “full corn” – this is the fruit. This is a stage in which the believer is bearing fruit, which honors and glorifies God.
This growing process takes time; in believers, each may grow at different rates. Let us not compare ourselves to others, but do what we can to be fruitful to God.