I meant that nobody's actually explained it (that I've seen).
there's a book written about every subject known to man, and plenty of those are about expression in art. such scholarly sources are probably better at explaining than we are to someone who just doesn't understand it by looking.
You are right, on the one hand, an image does not necessitate art in the same way that sound does not necessitate music, yet most people can recognize music and art readily enough. Thereby no, not all images have expression.
Furthermore, not all art is expressive. there is a great deal of art that tries to stay away from expression. Here is a short list of general artistic qualifiers and their "antonyms". Please bear in mind that not only are these only vague descriptors, but that even those that seem to conflict are not by any means mutually exclusive.
Naturalistic - Of or mimicking nature as close as it can be experienced by the eyes (and, at times, the hand).
Abstract - Not intending to appear or feel like nature.
Representational/Objective - Intended to denote real or plausible objects, places, or events.
Non-Representational/Non-Objective - Not intended to denote real or plausible objects, places, or events.
Mannered - Intended to demonstrate technical prowess; to serve mundane purpose.
Expressive - Intended to demonstrate emotion; to serve "artistic" purpose.
then there is further qualification within Expressive pieces, based on whether the expression comes from the artist or the piece itself. Laocoon and his sons
by a Rhodian collaboration and Ugolino
and sons by Carpeaux are both pieces which contain very expressive subjects, and these evoke personal reactions from the viewer (or at least, they should!), but the hand that made them was very measured, mannered, and NOT what is considered to be expressive.
Similarly, Piet Mondrian
produced some works that was intended to evoke emotion, but were by themselves very mannered, while Jackson Pollack
tended to produce works that were purely expressive.
It continues to be confusing, however, because many artists manage to be both meticulous AND expressive. Another work by Mondrian
demonstrates his breadth of character. Furthermore, desperation and haste does not always mean expressive, as such 'fits of inspiration' only demonstrate what the artist feels is a great idea and not necessarily one of emotional importance.
The biggest kicker though? Not all expression is expressionism. Expressionism deals primarily (and some would argue, exclusively) with "big" emotions, overwhelming sensations. Reflection of calmer, more passive feelings is often overlooked in talking about expressionism because (in my perhaps overly-critical opinion) many of the people* who get all hot and bothered by splashy red paint and piss christ don't always take the time to appreciate simpler things. To say that Monet's lovingly rendered, meticulously rendered, intimately
rendered gardens are without expression is to piss in the face of art (to express my disdain politely).
In the end i think it still just comes down to feeling. There is, at least to those who appreciate art, a tangible
presence of the creator's hand in all art, and it is very easy to tell which hand was forced, which hand was passionate, which hand was timid, which hand was gentle, and so on.
*(and by that i mean one in a million - 99.9% of good artists are intelligent. still....there are a lot of dicks; i could be one for all i know)