Memory is a private library, collected by experience. In its stacks are the happy memories we cherish and revisit, and the slim volumes of recollection we had half-forgotten that return to us as we browse through the present. And in another section of every mental library are the unpleasant memories: the tragedies, the failures, the embarrassments and the traumas. Most of us try not to dwell too long in that part of our personal literature, but we are still drawn there from time to time, despite the pain.

Science is about to change that. New research has discovered that certain “amnesia” drugs can block, dilute and even delete unwanted and unhappy memories. We could become, in effect, the curators of our own memory-libraries, chucking out or sealing up the volumes that distress us, leaving only shelf upon shelf of happy reminiscences.

Memories can now be manipulated. Neurologists have discovered that powerful emotional experiences trigger specific hormonal reactions, making some memories more vivid and painful than others: that is why you remember 9/11, but not what you were doing the day before. Studies at universities in North America, however, have found that the drug Propranolol (originally developed to treat heart disease) can inhibit the stress associated with specific memories, even decades after the events themselves, effectively reducing the pain of recollection.

More remarkable still is the discovery by scientists at New York University that certain memories in rats can be erased entirely. The rats were trained to associate two distinct musical tones with a mild electric shock: when they heard the notes, they braced for the shock. Then some of the rats were given the drug U0126, which induces amnesia, when they heard one of the tones: thereafter, the rats still reacted to the first tone, but did not flinch when they heard the second. The memory of the shock had been expunged. The scenario imagined in the 2004 film Eternal Sunshine of the Spotless Mind, in which the memory of a failed romance is scientifically erased, is no longer a fantasy.

The research is aimed at treating post traumatic stress disorder (PTSD), the legacy of pain and misery left on the mind by horrific experiences; yet the discovery that memory may be tweaked and modified carries much wider implications not only for medicine, but for the nature of humanity itself.

There is already an Orwellian term for such treatment – “therapeutic forgetting”. If we can manage and dilute memory after serious trauma, will science not also be used to rub out or water down other painful memories: divorce, bereavement, the shock of a terrorist attack or even what you did at the office party?

Plastic surgery was also pioneered to tackle a serious medical problem, the horrendous facial injuries suffered by combatants in the First World War, but has since become an accepted technique to improve on nature and hold back age. Cosmetic neurology may be next. Don’t like the shape of your remembrance of things past? Give your memory a nip and tuck.

Our memories – the bad, the good, the quotidian – are what define our personalities. Tinker with the emotional tonalities of remembered events, and we interfere with our very natures. Distress, anxiety and sorrow are the foundations of empathy, for without recalling unhappiness, how could we understand it in others? Memory is a part of evolution: the fittest memories survived because they remembered that the creature with the big teeth in the grass should be avoided.

Traumatised soldiers returning from the battlefield could be given drugs to make the memory more comfortable one day. But if a pill can numb the guilt and horror of conflict, then the truly horrific nature of war could be obscured: soldiers are no longer human beings but fighting drones, able to sluice away the bloody memories with pharmaceutical forgetfulness.

If the memory of terrible things could be dulled, the world might be more contented, but less real. Holocaust survivors might have lived happier lives had they been able to erase the dreadful memories, but our understanding of that great evil would be immeasurably lessened: their memories are our conscience.

Should entire groups of people self-medicate against memory? The victims of Hurricane Katrina, for example, or the population of war-torn Afghanistan? That could take the sting out of memory, but it would also blunt the point of history.

The scientists behind the amnesia drug research argue that since we already use chemicals to treat schizophrenia, stress and depression, then drugs to tackle painful and debilitating memories are the next logical step. There is nothing noble, they say, in the horrible, destructive cycle of post traumatic stress.

The newfound chemistry of remembrance and forgetting has the potential to shape humanity in the most profound ways, yet regulators have not even addressed the issue of whether such drugs could be legally used by individuals to reorder and revalue their memories without a pressing medical reason.

Some ravaged lives will surely be improved by easing painful memories, but most would be diminished. As anyone knows who has observed the slow, cruel larceny of Alzheimer’s disease, the erosion of the sad memories is just as tragic as the elimination of the joyful ones.

Jane Austen wrote that “if any faculty of our nature may be called more wonderful that the rest, it is memory. . . the memory is sometimes so retentive, so serviceable, so obedient; at others, so bewildered and so weak; and at others again, so tyrannic, so beyond control.”

The tyranny of memory should be endured, even embraced. To do otherwise is to beckon the final forgetting a little closer.

Times Recommends

• It’s the beginning of the affair
• Afghanistan: still a price worth paying
• Heroes of the downtrodden