Archivists of the obvious

What turns a humble object such as the postcard into a collector's item? Through accumulation, even

Postcards are an invention, like the postage stamp. So they have a beginning in history, and they have an end, like the telegram, the petit bleu, the carte de visite. Like the ostrakon, the lead tablet at the buried spring, with its scratched imprecation or common abuse, like the impression of gold in hot sealing wax, like all the technology of the wedding video, like the hand outlined in ochre on the cave wall (where would you find the ochre? where would you find the cave?) - but unlike the letter, unlike the portrait, the self-portrait, unlike the signature. Unlike any of those simple gestures by which one being says to another: I was here.

I saw this patch of cement drying on the pavement, and I signed it. I came to this temple, and I happened to have my chisel in my pocket. Your van was filthy dirty, so I wrote a message on it, divulging something unreliable about your private life . . .

Such messages are the product of a momentary exuberance, and their recipient is an imaginary public, whereas these postcards are the considered record of a moment, and all their recipients were known to the senders.

Hello. It's me. It's us. This is the spot on the mountain, this is the boarding-house room, this is the seafront. We got here. We made it. Don't you wish you had made it with us? Don't you wish you were here?

The technology dies. The desire persists. It wanders on and finds a new technology. Years later, looking back on this humblest kind of memento, as the exhibition of Tom Phillips's collection at the National Portrait Gallery shows, we find that the postcard begins to speak to us in a new way, as from an irrecoverable world. The first meaning it had has long since been forgotten. Now it has a new meaning. It has become a collectable.

There are two kinds of collecting: the selective and the accumulative. In the first, the collector seeks to assemble only the best examples of a class of object (paintings, sculptures, porcelain). The collection improves as its quality, but not its quantity, increases. With this method, sacrifices may continually be made, as objects of lesser worth are sold to acquire more desirable items. The number of entries in the inventory may remain static over the years, but the collection is seen to advance through substitution, or through a process of "trading up".

Pepys's Library - the one for which the first known purpose-built bookcases in England were made - was intended to comprise "in fewest Books and least Room the greatest diversity of Subjects, Stiles, and Languages its Owner's Reading [would] bear". Three thousand volumes was the target, in 12 bookcases. When Pepys acquired a superior version of a book, he discarded what was inferior. If he read a book he didn't like, he got rid of it. He always kept a sense of scale.

In the second, accumulative type of collection, the significance of the individual object is seen to grow through its keeping company with such a large number of items of a similar kind: one Gabon stamp may be neither here nor there, but 50 Gabon stamps act as a spur to the acquisition of 50 more. And as the ceiling is reached, as all the Gabon stamps seem to have been tracked down, a kind of restlessness sets in - Cameroon suddenly becomes interesting and desirable from the collector's point of view. Soon it is no longer a matter of forming a collection. Multiple classes of object have begun to occupy the collector's attention.

A formidable representative of this cast of mind was the tenor Evangelista Gorga (Rodolfo in the 1896 Turin premiere of La Boheme), who in 1899 retired early from the stage in order to devote himself to his collections in Rome, which occupied the remainder of his long life (1865-1957). He was a connoisseur of musical instruments (he had about as many instruments as Pepys had books). He collected ancient arms, fossils and toys of all epochs, medical equipment and surgical instruments, tools of all trades and professions, as well as bronzes, terracottas and objects in ivory or bone, until he had 30 distinct collections comprising a total of 150,000 items.

To house these he rented ten apartments in the same building (285 via Cola di Rienzo), where the 30 collections were installed without inventory or catalogue: the tobacco museum, with its pipes, pouches and cigar cases; the prints and drawings; the coloured marbles; toilet items from all ages; the health museum, itself including around 20 pharmacies from periods between 1000BC and the 19th century; the inscriptions; the artistic and scientific library, ancient and modern; the Risorgimento collection; the cookery equipment of every epoch.

Before too long he was bankrupt and his collections under sequestration by the state. But he had done some good with all his mania, and some of his collections still exist for public benefit and pleasure.

And it is right to say that this kind of accumulation has a point. The significance of a jar is indeed brought out by its correct placing in a pharmacy. The significance of a pharmacy is indeed enhanced by the comparison - if such could ever be achieved - with 20 other pharmacies down the ages. One might contend that it was wrong of Gorga to rent ten apartments (to make a collection of apartments), when it must surely have been cheaper to buy a whole building. But that is a rather prosaic argument to put up against the encyclopaedic vision of the collector, one of whose categories comprised oggetti di tutto lo scibile, dall'arcaico ai tempi nostri - objects of all knowledge, from archaic times to our own.

Flinders Petrie, the great Egyptologist, had a plan for a museum that would have solved Gorga's problem. He wanted a large tract of land to be purchased somewhere in the Home Counties, on which would be placed a simple modular structure sufficient to hold the museum's collections as they then were. In due course, if, as was likely, Assyria yielded up some great wealth of treasure, a further module would be added to the museum to accommo-date the finds. If cartloads of carvings arrived from Africa, a corresponding department could be extended along lines already envisaged. Ordering a new wing to be built, in this vision, would be simplicity itself; the whole kit might be sitting there, ready for assembly. I imagine that Petrie had in mind some kind of pattern like a snowflake crystal, which would simply grow and grow until that patch of the Home Counties was museumed over.

Collections of such a character need space. Alternatively, one may choose to collect objects that are by nature modest in their requirements. Even Pepys, within his carefully scaled library, had volumes of prints and a collection of broadside ballads - accu-mulative collections within his selective framework. And we will always be grateful to those snappers-up of ephemera who thought of saving what was in their own day disprized - those who in our times, for instance, have been keeping track of the prostitutes' cards that have littered the telephone booths of London.

To such pioneers, such archivists of the obvious, there is nothing that cannot be collected. The trick is to think of the category . . . and then to persist. Two such collectors, in an article I read not long ago, were dri- ving on their way to make a purchase when one stopped the car and approached a hitch-hiker, offering him $25 for his cardboard sign. On the spur of the moment, he had conceived the plan to make a collection of hitch-hikers' cardboard signs.

The example illustrates the paradigm. The individual object is of no great worth on its own. It is only through accumulation, only by becoming one of a category, that it has any great chance of engaging our interest. And this particular case seems particularly unpromising. But one has to remember that all such ephemera, by definition, must once have seemed unpromising. The "Wanted" poster from the Wild West, which today would be such a find, or the printed advertisement for the slave auction, were once trash.

Astonishingly common things have a way of becoming astonishingly rare. For instance, the pious Victorians who printed and handed out tracts by the thousand were creating a class of object that would become transcendentally scarce. I have seen many a papyrus from the ancient world, but I am not entirely sure that I have ever seen a real Victorian tract, and those scholars who work in this field are apparently hampered by the fact that the British Library's tract collection was destroyed by bombing in the Second World War.

But these postcards are not rare. They never were. They were made to be treasured by those directly involved in them - not for a moment by anyone else. But they were made in such quantities that, when they lost the significance, when their sitters died and their identities were in due course forgotten, still, by their sheer numbers and because they were not bulky, they could pass through a period of valuelessness into a new life as objects of curiosity.

So much that we admire today has passed through that period of disregard, that dangerous prelude to value. I remember in my childhood how the provincial auction rooms were filled with passed-over lots, those rosewood writing cases that opened out to form a desktop. They seemed beautiful to me then, with their brass-bound corners and their mother-of-pearl inlays, their square ink bottles and their "secret drawers", but they were a drug on the market, and the auctioneers despised them almost as much as they despised pianos.

I think of them sometimes as I throw out yet another fax machine, or wonder if I will ever really use a typewriter again. Will people say of me and mine: they threw out their fax machines, just as their ancestors threw out their harpsichords?

Once they meant so much. Then they meant nothing. Then taste and curiosity took pity on them, and they began to mean something again. And so people began collecting these postcard portraits, these seaside souvenirs. And Tom Phillips, who made this research, these purchases, tells us he has assembled 50,000 cards, and sorted them into 120 categories, of which he offers us this wonderfully eloquent sample.

And we see here the strength of the accumulative method, for the categories do indeed come as a surprise. Who would have predicted that the aspidistra (which we remember only as a joke) would be such an important prop as to establish its own genre? Who could have fore- seen the interest provided by multiple views of the backyard of the two-up two-down?

What we could well have predicted, though, is the principal source of interest: a chapter in the history of self-presentation, as defined through a given technology, in a period normally delineated by the two great wars. We are warned by our collector/curator not to expect to be able to date these postcards accurately, and he is right, I think, to discourage the desire to define too clearly our feelings about what we are seeing. It is what we find elusive that keeps us happy wandering through this postcard museum, this exorbitant accumulation of lost selves.

"We Are The People: postcards from the collection of Tom Phillips" is at the National Portrait Gallery, London WC2 (020 7306 0055) until 20 June

James Fenton's most recent book is An Introduction to English Poetry (Penguin)