Of all human vanities, there is none greater than to contemplate one's "place in history". Posterity reserves its bitterest mockery for those who presume to foresee how they will be judged in retrospect. Hitler's "Thousand Year Reich" was annihilated just as comprehensively, and even more swiftly, than the empire of Shelley's Ozymandias, the "King of Kings", who proclaimed: 

"Look upon my works, ye Mighty, and despair!"
Nothing beside remains. Round the decay
Of that colossal wreck, boundless and bare
The lone and level sands stretch far away.

Yet, with no greater reason than an accident of the calendar, unprecedented numbers are asking how they will be recalled by history - if not as individuals, or as nation-states, then as the children of an epoch. Scribes and scholars pose the question, "How will the Twentieth Century be remembered?"

There are three obvious answers: as the century of technology; as the century of inhumanity; and as the century of environmental vandalism.

As to technology, it is undoubtedly the case that the Twentieth Century's progress - if "progress" is the right word - exceeds by a factor of many times humanity's technological development up to the beginning of the century. But in truth, the same could equally be said of the Nineteenth Century, of the Eighteenth Century, and even of the Seventeenth Century. Technology has continued to expand exponentially, and it is arrogant to assume that the great technological achievements of the Twentieth Century will be viewed by future generations as having a significance equivalent to the invention of the printing press or the steam engine.

As to inhumanity, it could hardly be doubted that the Twentieth Century has witnessed, on more than one occasion, what Winston Churchill accurately described as "a monstrous tyranny, never surpassed in the dark, lamentable catalogue of human crime". But the horrors perpetrated under Hitler, Stalin, Pol Pot, Idi Amin, Duvalier, Pinochet, Saddam Hussein, Milosovich, and others of the Twentieth Century, are remarkable for their scale rather than their originality. The "dark, lamentable catalogue of human crime" includes villains who were (arguably) equally as wicked, from Caligula to Robespierre, from Attila the Hun and Genghis Khan to Ivan the Terrible, and from Vlad Dracul ("the Impaler", from whom the Dracula legend originated) to the Spanish Inquisitor-General de Torquemada.

Nor is the Twentieth Century's environmental vandalism anything more than a continuation of what began with the Industrial Revolution. Although the problem is magnified, at least it can be said of the Twentieth Century that mankind finally recognised the importance of protecting the ecosystem, and took the first (albeit inadequate) steps towards doing so.

One's place in history is not fixed by what came before, but by what came after. Salieri may have been the greatest composer of his day, introducing harmonic devices and other musical techniques which were unknown to previous generations of composers. Yet Salieri has become a footnote to the history of music, remembered only for his (much exaggerated) rivalry with the younger Mozart, because, whatever Salieri did, Mozart did better. Sir Isaac Newton modestly acknowledged the contribution of his predecessors to his own success as a mathematician and physicist: "If I have seen further it is by standing on the shoulders of giants." Yet it is Newton, rather than the giants on whose shoulders he stood, on whom history has conferred its greatest accolades. 

Similarly, the Twentieth Century will be remembered for what comes after it. Let us hope, indeed, that it will be remembered for centuries to come as the era of the fiercest wars, the worst acts of terror, the most appalling abuses of human rights, the most egregious environmental vandalism, in the history of humankind. For if the Twentieth Century is so remembered, it will only be because the world has become a significantly better place in the Twenty-First and succeeding centuries. 

Nobody can predict, with certainty, whether this will be so. But - vanity of vanities - the Officious Bystander proposes two more humble predictions.

First, that the Twentieth Century will be recalled as a turning-point in the attitude of civilised nations to the use of military force. At the dawn of the Twentieth Century, and at least for its first half, even civilised nations - by which I mean those with well-developed liberal-democratic traditions - considered acceptable the use of military power to achieve territorial, economic and political advantages. Though Nuremberg declared it a crime to "wage aggressive warfare", there is a cogent argument that at least one "civilised" country (according to the definition mentioned above), namely the United States, did not resile from the use of force to pursue territorial, economic and political ambitions, at least until the Vietnam War ended. Russia, which does not have a well-developed liberal-democratic tradition, maintained that attitude into the 1980s with its expansionist adventure in Afghanistan, and arguably continues that policy in Chechnia.

Still, over the second half of the Twentieth Century, there has evolved the notion that the military power of civilised countries exists for a single purpose - as Woodrow Wilson put it, in seeking the approval of Congress for America's intervention in the First World War, to make "the world ... safe for democracy".

The extent to which this precept has determined the military policies of the world's civilised nations - to the exclusion of considerations of territorial, economic and political self-interest - is debatable as regards conflicts like the two World Wars, Korea, and the Gulf War. But the last two major military endeavours of the Twentieth Century - the NATO intervention in Kosovo and the Australian-led, UN backed intervention in East Timor - must surely be judged by any impartial observer as largely, if not entirely, altruistic. In a general sense, no doubt, there is an element of self-interest amongst NATO countries in restoring stability in the Balkans, as there was in restoring a friendly administration to the oil-rich state of Kuwait in the Gulf War. But Australia can certainly hold its head up high, and declare that we risked prejudicing our own self-interest with a great and powerful neighbour, to intervene in East Timor exclusively for humanitarian reasons.

This is a new phenomenon. It is difficult to identify any other time in history when military force has been used entirely for a benevolent purpose, without any thought of self-interest, and even contrary to a country's economic interests. What makes the East Timor intervention all the more laudable is the sheer boldness when a country of fewer than 20 millions - a country which is far from being a world power - risks offending a country with a population more than ten times greater, and a GDP almost twice our own.

A closely related development is the resolution by civilised countries that, whilst the world is made safe for democracy, it is made unsafe for those who practise genocide, terrorism and other crimes against humanity. Although General Pinochet ultimately escaped trial and punishment, his case creates a remarkable precedent. The House of Lords swept aside issues of territorial sovereignty and executive immunity to declare that crimes against humanity may be tried and punished wherever the offender can be apprehended, and regardless of the offender's princely or presidential status. Not since Roman times, when pirates were declared hostes humani generis - enemies of all mankind - has international law set its face so resolutely against a particular scourge, to declare that the miscreant shall have no shelter or refuge anywhere on the planet.

The Officious Bystander's other prediction is more ambivalent. Undoubtedly, the Twentieth Century will be remembered as the time in mankind's history when we achieved supremacy over infectious micro-organisms. What remains to be seen is whether this supremacy will prove to be temporary or enduring. 

Prior to the discovery of Penicillin by Sir Alexander Fleming, and its clinical application by Baron Florey of Adelaide, humanity was at the mercy of bacteria. Prevention of infections, through general hygiene and the use of antiseptics, was possible; there was no known cure. Infant mortality caused by bacterial infection, and the premature deaths of otherwise healthy men and women, were a fact of life. In many cases, the only treatment was amputation, and even this drastic remedy often failed to prevent the spread of infection.

The last 60 years represents the only period in the history of our planet when human beings have not lived in fear of bacterial infections. But who knows how long this will continue? The over-use and misuse of antibiotics has increasingly led to the development of more virulent strains. We are beginning to see the evolution of bacteria which resist every known form of antibiotic. 

The war between the Earth's most advanced species of organisms, and its simplest and most primitive organisms, will continue well into the future. The notion that infectious bacteria can ever be totally eliminated, which was prevalent in the 1960s and 1970s, is now plainly a pipe-dream. The most that we can ever hope to achieve is a kind of armed truce, whilst human ingenuity races to develop new and different responses to the ever more hardy bacterium.

Or possibly - just possibly - an entirely different approach will prove a more enduring success than antibiotics. Current research into the development of bacteriophages - viruses which kill bacteria - looks promising. There is a logical attraction to the idea that phages can succeed where antibiotics are beginning to fail, because phages, as living organisms, are able to adapt and mutate just as the bacteria themselves develop more resistant strains. Another approach which has been mooted is the deliberate reintroduction of non-resistant bacteria, in the hope that this will dilute the bacterial gene-pool, and reverse the trend towards antibiotic resistence amongst common bacterial pathogens.

In the Twenty-First Century, we may, with some luck, stay one step ahead of the evolving bacteria; or we may lose the war altogether. On any view, the second half of the Twentieth Century will be remembered as the only period in history when humankind had bacteria at our mercy.