This page will provide some added direction to help you get over some "bumps in the road" involved in identifying/analyzing imperfect and aorist verbs.

While many verbs may be immediately recognized and parsed with the information provided up to this point, there are others that will not because of morphological adjustments that have been made. These include possible changes to the epsilon augment, amalgamation involving the aoristic aspect morph sa, as well as other variations that may only be learned through observation. 

(1) What you are already familiar with is the additive morpheme, the ev prefixed to the stem. This is known as a syllabic augment. E.g., in e;luon (impf act ind 1 sg > lu,w).

(2) When the verb begins with a short vowel, the augment consists of a process morpheme resulting from the lengthening of the short vowel to a corresponding long vowel. This is known as a temporal augment. E.g.,

evgei,rw becomes h;geiron
a;gw becomes h=gon
ovfei,lw becomes w;feilon

(3) A verb beginning with a long vowel or diphthong will have a zero morpheme augment, since it will essentially remain unchanged. E.g.,

euvri,skw becomes eu=ron

There is more important information about augments in Black, Learn, §51 (particularly in the small print section).

The aoristic aspect morph sa will be modified in accordance with the same rules of amalgamation we learned when discussing amalgamation in the future tense.

So, for example, the first aorist active of ble,pw is e;bleya.

There is a table of examples in Black, Learn, §50.

We have been using the term lexal and stem interchangeably. The advantage of the word lexal is that it denotes the meaning of a given word that is associated with its particular lexal morpheme. There are rougly 1,000 lexals in New Testament Greek.

As we have seen, the lexal for imperfect and first aorist verbs is usually (although not always!) identical to the stem of their respective lexical entries. Hence, parsing imperfect and first aorist verbs is rather straighforward.

Second aorist lexals, however, will almost never match their lexical entry (i.e., present tense stem).

There are a number of possible reasons for this variance. In some cases (as in h;gagon) the lexal has been modified, in this instance through reduplication (or doubling) before a temporal augment is applied. One may observe a myriad of other slight modifications to lexical entry stems (e.g., pa,scw becomes e;paqon).

There are other instances when the lexical entry bears no resemblance whatsoever to the form under analysis. This phenomenon is not unique to second aorist verbs, but is well-illustrated in the last five lines of parsing above. The forms being parsed are known as suppletives. Some verbs became "defective" in that certain forms dropped out of use. Forms from other etymologically unrelated verbs were then used to "fill in the gaps" left by the defunct forms. Hence, e;fagon is used as the 2aor act ind of evsqi,w, and so on for the last four listed above.

One more feature needs to be observed concerning the identification of aorist verbs. There are instances when second aorist forms appear to have first aorist endings (minus the s). For example: