Early on when I started writing poetry, I read a quote somewhere, by I know not who, which went something like this: "If it can be said just as well in half a page of prose, it's said better in prose."

It goes to what something is, and what it isn't, in its nature. A poem which adds nothing to the purely literal and abstract content, is strictly speaking not a poem, at least in the post-Poe, post-Romantic era understanding of the word.

What does that have to do with art, and Marcus Aurelius?

Well, I happened to stumble across the webpage of Belgian conceptual artist Wim Delvoye. Mr Delvoye is the creator of the Cloaca Machine, a work (or rather works) of art which emulate the human digestive system. You stuff food in one end, and get poo out the other. Said poo is then packaged, branded, and sold as nifty works of art in their own right.

So what is art? And what is poo?

This is where you should imagine Hannibal Lecter in "The Silence of the Lambs" whispering in your ear.

Lecter: "First principles, Clarice. Read Marcus Aurelius. Of each particular thing, ask: What is it in itself? What is its nature?"

The point is that the Cloaca Machine, along with a lot of other modern conceptual art, also comes fairly close to being something which adds little to what could be explained in a sheet of instructions, or a page or two from a science text-book. It's all head, and no heart. Though you could claim there's guts, guts galore in fact.

So what's the alternative to the poo? A lot of people would probably answer something like Thomas Kinkade. And who is this Thomas Kinkade, you might ask. Well, he's an American artist who's become very rich selling some rather bad paintings. And I do mean very rich.

He specialises in idyllic figurative paintings bathed in the warm glow of patriotism, faith and family values. You know, the stuff you find on maudlin postcards and prints hung on the walls of lavatories.

A devout Christian who calls himself the "Painter of Light," Kinkade trades heavily on his beliefs and says God has guided his brush — and his life — for the last 20 years.

"When I got saved, God became my art agent," he said in a 2004 video biography, genteel in tone and rich in the themes of faith and family values that have helped win him legions of fans, albeit few among art critics.

Aside from the "inspirational" themes being a none too shabby business strategy in a contemporary Untied States caught up in one of its regularly recurring religious fervours, the point is that he sells a mind-boggling number of very bad paintings. He's the sort of artist that makes the practitioners of high art, critics and academics shake their heads in saddened disbelief at the lack of taste (and breeding?) among the hoi polloi.

But in a way Kinkade is a product of modern serious art's disconnect with mainstream audiences. It might be enlightening again to try to establish a first principle. Do people need art? For mere survival? Not in any meaningful sense of the word. But people, being equipped with big number-crunching brains, that more often than not go mostly idle, do have a need to surround themselves with aesthetically pleasing manifestations of order. The modern angst that the universe might in fact not, in the end, make any sense that we can fathom, with senses and faculties designed to do just that, actually makes for an even stronger yearning for such confirmations that there is an underlying order that can be discerned in, or imposed on, the universe.

Does the ordinary man and woman in the street have the capacity to embrace a better standard of art than Kinkade? Yes, they have in the past. Can (should is another matter entirely) a majority of them be "taught" to appreciate Klee or Pollock? Probably not. Having in a very real sense been abandoned by high art, and never having been taught the basics of artistic technique and the history of art, they are then left with such third rate stuff as Thomas Kinkade. Which only confirms their low-brow nature to the cognoscenti of the arts, and the futility, and down right danger, in trying to appeal to them.

In my view this has worked as a feedback-loop, resulting in bad art at both ends of the spectrum. Kinkade's art is of course inferior in many obvious and even technical ways. But the flaws of modern high art are a bit more tricky to pin down. I'd venture that the heart of the matter is its over reliance on abstraction. And no, by that I don't primarily mean the use of abstraction in the work, but its need of an abstract exegesis to justify its nature as art.

Let me try to illustrate the point. We have few inklings as to what the works of art in say classical Greece meant to the the artists who made them, or the people they were made for. There are whole layers of religious and aesthetic thought that underpinned this art, which is lost to us. Things that were too self-evident to people of the time to write down, and which can not be dug up out of the ground by archaeologists of today along with the carved pieces of marble.

Yet, even shorn of its cultural context, no one at any time, or from any culture, however alien, would mistake them for anything other than art. That is not to say that we haven't surrounded these works with our own abstract notions of their meaning and significance. But their nature as art could never be in doubt. The same would in all probability be true of a work by Rodin, to bring it closer to our own age.

Modern art, and in particular the now dominant conceptual art, relies heavily on an audience which is educated, not primarily in art, but the language of art, as the work's justification as being art in the first place is all about context and cultural connotations. Let's once again use Duchamp's iconic work "Fountain", which was recently voted the most important work of art in the twentieth century, and which is in fact a porcelain urinal Duchamp signed "R. Mutt" in 1917 and entered in an exhibition.

And a convincing case can be made, and has been, that "Fountain" does make an important statement on art and its allotted position in our society, and that it broadened the scope for art when it was in danger of calcifying into rote mannerism and, yes, kitsch.

But let's say the Pompidou Centre in Paris was abandoned, left to the ravages of time, and in the end was buried and forgotten. Then, millennia from now, future archaeologists from some culture wholly unconnected to our own, knowing little of the true nature of twentieth century European thought and art, were to dig up the site and come across the "Fountain". Would they recognise it as art? Or would they scratch their heads for a while before arriving at the conclusion that these were people who knew how to design rather handsome urinals?

In short, would the art of Duchamp, and his modern followers, stand the test of time, in the literal sense of the word? And if it could not, if the work is not "whole unto itself", but is incomplete without an abstract and esoteric exegesis, leaving the "true" work of art accessible only to the initiated few, then is it deserving of the name? And is it in fact much better than the sentimental Kinkade paintings those same archaeologists dug out of the lavatory?

Or as it says on the Cloaca poo-shopping page:

Buying Cloaca shit has never been easier!
Use your creditcard (Visa or Mastercard) through our secure online shopping system to obtain a fine specimen of contemporary art.

Indeed.