Now that we've covered some of the theory of aspect, we turn to examples. We'll touch only briefly on aspect in simple sentences since it is in the relationship between main and subordinate clauses that aspect is most likely to be confusing to beginners. Traditional Greek instruction, in particular, is apt to cause problems: when you've been told the aorist is primarily a past tense, the aorist imperative is going to seem puzzling: "raised the sails" doesn't make much sense.
We are going to omit conditional sentences from our examples. What we have to say about aspect applies to these, too, and in fact simplifies the usual inventory of conditional types. But explaining the additional role of tense and mood would distract from our focus on aspect.
In the discussion below the most important thing to keep in mind - and which we'll repeat a few times for good measure - is that only the indicative verb forms of the present, aorist and perfect may have tense. All the rest do not.
Verb forms made from the durative stem (traditionally known as the "present" stem) show imperfective aspect. In the indicative this includes the present and imperfect conjugations: ble/pw I see, I am seeing, e)/blepon I was seeing.
Above we said that the imperfective aspect shows an action in progress, in the middle of going on. So, in non-indicative clauses the present forms view the action as on-going, generally at the same time as the main verb. For example, badi/zwn le/gei (while) walking, he speaks. Here the present form le/gei does indicate tense, but badi/zwn indicates aspect, namely, that the walking is seen as ongoing at the time of the speaking.
If we change the tense of the main verb: badi/zwn e)/legen, (while) walking he was speaking. Again, the main verb indicates tense, the participle aspect.
Infinitives and imperatives formed from the present stem also indicate aspect rather than tense. ou)/ fhsi ou(/tw le/gein he denies that he is saying so. The semantics of the various imperatives, positive and negative, can get a little complex, but when when a speaker gives a command in the present imperative he sees the action as on-going, possibly taking a while: tau=ta poiei=te do these things!
Verb forms made from the punctual (or aorist) stem show perfective aspect. Most of the time the aorist indicative definitely has both tense (past) and aspect (perfective). a)ph=lqon they went away. One exception is the gnomic aorist which is used to express general truths, o(/j ke qeoi=j e)pipei/qhtai, ma/la t' e)/kluon au)tou=, Whoever obeys the gods, him they listen to especially. Here the aspect comes to the fore and seems to emphasize the singularity of the truth uttered.
The rest of the non-indicative forms from the aorist stem indicate punctual aspect only. In practice this nearly always means the action of the aorist form occurred before the main verb action.
tau=ta le/gousa a)ph=lqen (while) saying these things, she went away
tau=ta ei)pou=sa a)ph=lqen having said these things, she went away
To give a command for a single action, or an action viewed as a single event, Greek uses the aorist imperative: tou=to poih/sate do this!
Here are some more examples, adding subjunctives and optatives. Note the difference in meaning.
ei)=pen o(/ti gra/foi he said that he was writing.
ei)=pen o(/ti gra/yeie he said that he had written.bou/lomai pe/myai I wish to send.
bou/lomai pe/mpein I wish to keep sending.e)/rxomai i(/na e(/pwmai I come in order to keep following.
e)/rxomai i(/na e(spw/mhn I come in order to follow.h)=lqon i(/na e(/poi/mhn I came in order to keep following.
h)=lqon i(/na e(spoi/mhn I came in order to follow.
For a fuller example, here is the first line and a half of Babrius 78 (according to the 1986 Teubner), which has four verb forms:
ko/rac nosh/saj e)/lege mhtri\ klaiou/sh|:
"mh\ klai=e, mh=ter, ..."A crow that had gotten sick was saying to his crying mother // "don't cry, mother ..."
The first, nosh/saj, a masculine nominative singular aorist particple, is from nose/w "to be sick", and agrees with the subject, the crow. e)/legen is imperfect, "was saying." From klai/w to cry we have two forms, a feminine dative singular present participle, and a third person present imperative. In my translation for mh\ klai=e I used idiomatic English in my translation, but as a present-stem imperative, it really means more "don't keep on crying, mother."
As noted above, the future tense forms in Greek have no fixed aspect. It can be imperfective or perfective as context requires. Nonetheless the non-indicative forms of the future can also have particular meanings which differ from the indicative in a manner similar to the present and aorist. Similar enough, at any rate, that a few comments for completeness seem in order.
In simple clauses, the future simply indicates the action will happen in the future with respect to the tense of the main verb. In English we use "would" in this sense in the example, he said he would go away. In Greek this is ei)=pen a)poporeu/sesqai. This is simply a matter of tense.
But the future participle and infinitive also show the idea of purpose. Now, if you say you will do something there is a sense of purpose in that, so this isn't too strange. Future participles have this meaning fairly often:
h)=lqe luso/menoj th\n qu/gatra he came (in order) to free his daughter.
h)=lqon e)gw\ pau/sousa to\ so\n me/noj I came to stop this rage of yours. (Iliad A.207., Athena speaking, so feminine participle)