But, Ialmisry, a picture can be symbolic too, surely? You say that:
A religious picture can portray how someone sees a certain scene or person, the icon shows how the Church sees the scene or person.
But pictures aren't just quasi-photographic records, are they? That's a very small slice out of art history.
Of course pictures and religious paintings can contain symbolism. Anyone who's taken an "Intro to Art" class will agree with you on that point.
So what makes an icon an icon, and not just another religious painting? The first thing would be that the iconographer (the person "writing" the icon) is following the canons established by the VII Ecumenical Council. This includes the two-dimensional style figures, and that no shadows are included in the icon. (An icon is to give off light, not receive light.) Another element to iconography is that the icon is not to be a reflection of the iconographer's personal ego or "style" but is to be consistant with the icons painted before him. Now while it is true that each iconographer will have his own little twist on things (after all, we are human) it's not to be immediately apparant.
For example, when one sees a painting by Caravaggio, one immediately knows "Oh, that's a painting by Caravaggio, and not Michelangelo." With iconography, it's not about the artist -- it's about the subject matter. One is focused on what is being potrayed, not who is potraying it.
Icons are not to be signed. (This made my paper on Andrei Rublev this past semester extremely difficult btw! lol)
A really good book to read (that isn't that long) is Pavel Florensky's Iconostasis
. It's only about 300 pages long, and unlike many other books on Orthodoxy, the text is not dry, and is extremely interesting to read. The other good thing is that it's available in Paperback, so it's not too pricey. (I checked, and it's available on amazon.co.uk)
I hope this helps clarify some things.