On "Parables" in the Quran, the way I see them:

Generally speaking, "parables" in the Quran are complex entities although most of them contain only a few words and very little else to indicate what is meant by them.

Here are some of them:

http://quod.lib.umich.edu/cgi/k/koran/koran-idx?type=simple&q1=parable&size=First+100

For instance:

[2.26] Surely Allah is not ashamed to set forth any parable-- (that of) a gnat or any thing above that; then as for those who believe, they know that it is the truth from their Lord, and as for those who disbelieve, they say: What is it that Allah means by this parable: He causes many to err by it and many He leads aright by it! but He does not cause to err by it (any) except the transgressors...

So what is the actual meaning of these things and what has that to do with something like this:

"The like of the hidden pearls" which occurs in one of the most transcendant of all the Suras and is called "The Beneficent". In my amateurish estimation, the Sura is all about the choices involved in selecting the benefits of the material world and those of the afterlife. In that Sura, it can be incredibly difficult to distinguish between "one garden" and the next. One garden contains pure maidens and youths with eyes like pearls and another garden with exactly the same thing. Mention is made of "fruits" but the fruits are "just like" the ones we are used to handling with our "material" senses but in one case, the syntax of a sentence conceals the relationship of "what" is being touched. This is, exegesis or "tafsir"...which is a dangerous sport in Islam and not one that I am in any way knowledgable about except to say "via" my own experiences in the material world that I know were not what others experiencing them with me, in other words at the same time using the same five senses, "thought they were". For instance, when the dog I had harbored for a couple of weeks got hit by a car right in front of myself and the owner of the dog who had mysteriously appeared just moments before to claim his dog. The man was a wretched individual actually and I knew it. Perhaps, not even a man. Ah. Now if people understood what I understand, I'd be incarcerated and diagnosed as "insane". Why? Because my view of reality is not what it ought to be according to the materialist world view which is predominant in our age and times. Predominant of course and terribly terribly wrong and leading to all sorts of aggressions and tribulations. So what is it about these parables that I find and others may not be able to see or understand?

Good question and beats me if I can manage to explain to anyone this monumental idea. The Sura called the Beneficent however, in my humble opinion, does it best because it is a Parable's Parable. And that is the best form of tafsir one can practice. That form is called, "allowing the Quran to explain the Quran" via reference and inspiration.

"The Qur'ân explained by the Qur'ân: The interpretation of the Qur'ân by the Qur'ân is the highest source of tafsîr. Many of the questions which may arise out of a certain passage of the Qur'ân have their explanation in other parts of the very same book, and often there is no need to turn to any sources other than the word of Allah, which in itself contains tafsîr. To seek to explain an aya from the Qur'ân by referring to another ayâ from the Qur'ân is the first and foremost duty of the mufassir. Only if this does not suffice, he will refer to other sources of tafsîr." from: http://www.islamic-awareness.org/Quran/Tafseer/Ulum/

Following: The parable of spiders.