It is the lengthy typescript of a slide-illustrated lecture, or lecture series, written and delivered by the late Hardwicke Knight.
It was discovered by Meg Davidson who has been working for some years on a biography.
Mr Knight has proved a far more complex subject than even his striking persona might have suggested.
The sources are more than usually rich and daunting.
They also include some gems.
The address is titled An Approach to Modern Painting and perhaps was delivered in the late 1950s or early 1960s.
It might have been at the Dunedin Public Art Gallery.
There may even be people who remember it.
There has been more discussion of art history in New Zealand and theorising about art than most people suppose.
Even so, this is a considerable as well as a most unusual document especially in the extent of the exposition and the originality of its theory.
It isn't about modern painting in New Zealand - it scarcely mentions it.
Its history is of overseas developments while the theory is intended as universal.
It was first written in 1950, elaborated after November 1954 and, as Mr Knight arrived here in 1957, it wasn't a New Zealand production.
But it was delivered here, its only form of publication, so it is part of our art discourse.
It says some things few would today - mostly off topic - some appalling and some unintentionally funny.
Did it amaze, offend, baffle or bore its audience?
It would be very instructive to know.
Its history is wide and deeply informed, although there's one glaring omission.
It reveals yet another subject of which Mr Knight was formidably knowledgeable and his comment on works is often excellent.
And he is revealed as a passionate admirer of the modern, holding it high above most preceding Western art, surprising, because he is usually remembered for his passionate attachment to things old.
He was a mass of contradictions all told, more evident as more of his thought is found. It didn't assist him as a theoretician but the theory is nevertheless remarkable.
With apologies to Mr Knight, I summarise.
Art works by expressing feelings and modern painting does this particularly well.
In the past European art in classical times, and from the Renaissance to the 19thC, employed linear perspective unknown elsewhere and not conducive to effective art.
From the late 19thC artists started to abandon this and early in the 20thC arrived at wholly abstract works "the most sublime expression in painting".
Before then painting had been used for conveying ideas, for example for the church, or imitating things, often in nature, neither of which helps to produce good art.
The artist can't work without a brain or a mind but these shouldn't dominate the body, the source of feeling, when one is painting or appreciating painting.
Feeling emanating from the body is wholly good.
The mind is the source of such negative feelings as hate.
Abstraction gets to the essence of the subject.
There is really no distinction between that and how the artist feels about it.
Composition (and perhaps the use of colour) is the means by which feeling is expressed by producing tension and movement which act on us as we look at the work.
In the history of modern painting the Impressionists (Monet, Renoir, Pissarro etc), were the last of the old - because they were still committed to realism.
The post-impressionists (Van Gogh, Gauguin, Cezanne), were the first of the new.
Or perhaps the Fauves and the cubists were.
Photography can and does express the essence of things and is therefore one of the greatest artistic mediums.
Nevertheless we shouldn't underrate the old masters.
Picasso and Leonardo can't be compared.
Modern painting was produced by specific causes, such as the return to the sketch and its assertion as a finished work, but also by more general social changes.
One was a desire for "truth in art".
Another was something more obscure which comparably produced Marxism, in opposition to, or a "contradiction" of, the spirit of the time when it emerged, but nevertheless was a part of that time and the present.
This is an expressive theory of art locating its value in what it expresses.
Such theories have significant advantages over older types and Mr Knight didn't invent the type.
What is unusual is his exclusion of intellectual things - ideas and information - from the range of things expressed which give art its kick.
Together with his construal of linear perspective as a constraint, rather than a useful tool, it has the startling effect of writing off most of Western art.
The theory is unsustainable but its airing here was remarkable.
It would be wonderful to hear from anyone who remembers it.
• Peter Entwisle is a Dunedin curator, historian and writer.
