In English, we are familiar with the idea that verbs come in three tenses that show the time when an action happens:

     Present tense - something happening now

     Past tense - something that happened earlier (like yesterday)

     Future tense - something that will happen later (like tomorrow)

In Greek, it's different and it may seem more complicated.  In plain statements of fact (known as indicative mood verbs), Greek verbs do tell you something about the time of an action.  But that's not the most important concern for a Greek.  Greeks were more concerned about the type of action, not the time. If you listen to scholars talking about this concept, you may hear the words "aspect" or "Aktionsart" (if you hang around German scholars!).  With minor distinctions, all these terms refer to the same set of ideas.  Let's explain it this way:

Greek verbs show three types of action:

1.      Continued action -- it describes something that is going on continually or repeatedly.

2.      Simple action -- it just tells you that something happened, without any extra information about how long it took or whether it has been completed.

3.      Completed action -- it describes an action that has been completed, adding the thought that there are results continuing afterwards.

Any of these three types of action can take place in the past, present or future.  For example, look at 1 Corinthians 3:6:  "I planted, Apollos watered, but God was causing the growth."  

The first two verbs are aorist, which shows simple action.  Paul describes his ministry as a single event:  he planted.  He was in Corinth for well over a year, but he is not emphasizing the length of time in this verse; he simply wants his readers to know that he did plant.  He chooses the same type of verb to describe the ministry of Apollos.  We don't know how long Apollos served in Corinth, but we know the simple fact that he watered.

The third verb, however, is in the imperfect tense, which shows continued action:  God was causing the growth.  This emphasizes the fact that God was quietly in action over the entire period of time.  Paul came and went; Apollos came and went.  But behind the scenes, God continually caused the church to grow.

As you study all the various Greek verbs, don't forget this concept!  It doesn't play a large role in English, so it's easy to overlook.  But it is one of the most important features of the Greek language.