Timothy Leary, the intellectual cheerleader of chemical transcendence, said that when he ate magic mushrooms in Mexico in 1960 he learnt more in four hours than in all his years as a psychologist.
Forty-four years later, seekers of knowledge need only take a stroll along one of London's famous high streets and visit one of the many 'shroom shops' to test his theory. Furthermore, they can do it without breaking the law.
To prove the point, many of the shop owners display copies of a letter written by a Home Office official which makes it clear that there is nothing illegal in the trade of freshly picked magic mushrooms.
But their legal sale appears to be about to end after ministers moved to tighten the loophole.
Under the current law the psilocybe mushroom, or magic mushroom is not a controlled substance but the hallucinogen, psilocin, that it contains, is classified as Class A drug.
Provided the gatherer does not commercially 'prepare' the mushroom - by freezing them, drying them or using them to make tea - before selling them they are not committing a criminal offence.
But the shift in policy signals a new zero-tolerance, meaning the sale of unprepared mushrooms could now be illegal.
The Home Office minister, Caroline Flint, has told shop owners that if they are selling magic mushrooms they are probably breaking the law.
Anti-drug groups have long warned that this legal loophole encourages young people to experiment with an hallucinogenic substance that can lead to nightmarish trips, stomach pains, sickness and, in some case, psychiatric problems.
In a letter to the Labour MP Paul Flynn, the minister advises: 'In the Home Office's view, a form of preparation and production has occurred by the sale of magic mushrooms in market places and shops or at other premises or at other sale points. Accordingly, those selling, or seeking to sell, the mushrooms at such premises are unlawfully supplying a product containing psilocin and/ or psilocybin.'
She adds: 'My officials are in contact with the enforcement agencies about how the law can be more effectively enforced.'
Her words have been backed up by action. On 7 July police raided three 'shroom shops' in Birmingham and one in Guildford, Surrey.
Other cases are already being prepared for court. In Canterbury, Kent, two defendants are facing the first ever Crown Court trial for intent to supply psilocin.
Celia Strange, the solicitor representing the defendants in the Canterbury case, detects a hardening of policy.
'It seems that it depends which police force you are dealing with. Some of the arrests have led to no further action even after the police have sent the mushrooms off for forensic tests. Others, however, appear to be going further.'
The Home Office letter displayed by owners of 'shroom shops', which was sent by the drug licensing section, spells out the long-accepted liberal position. It says: 'The courts have held that a person is not in possession of a controlled drug solely by reason of him being in possession of a naturally occurring substance - the mushroom ... It is not illegal to sell or give away a freshly picked mushroom provided it has not been prepared in any way.'
The magic mushroom industry understandably interpreted that as a green light to step-up trading. Advertising hoardings have sprung up across the capital promising a 24-hour door-to-door delivery service.
There are now estimated to be between 200 to 300 shops selling mushrooms and many other businesses trading online. Some of the mushrooms are home-grown but the bulk of the produce is imported from Holland.
The BBC Radio 4 programme, Law in Action, has reported that Customs and Excise makes hundreds of thousands profit in duty and VAT payable on the import and sale of the magic mushroom.
The new shift in policy has led magic mushroom shop owners to detect a whiff of government hypocrisy. 'How can one arm of government be criminalising the trade of mushroom and another be making thousands of pounds in revenues?' asked one shroom shop owner yesterday.
Paul Flynn describes the legal position as irrational: 'As far as I understand, it's legal to graze for mushrooms and go down on your hands and knees and eat them. But the key to the letter seems to be that the hand of man must not be involved. So does that mean it would be OK for chimpanzees or women and children to collect them?'
A HALLUCINOGENIC HISTORY
A group of mushroom statues found in Guatemala and thought to date as far back as 500BC has been interpreted as evidence that ancient people once worshipped the mushroom.
The first documented hallucinogenic mushroom experience in Britain took place in Green Park in London on 3 October 1799. A man identified only as 'JS' picked and ate a magic mushroom for his breakfast. It was reported that he found odd flashes of colour bursting across his vision.
But it wasn't until the 1960s that Western cultures began to use mushrooms recreationally as an alternative to LSD.
The banker and amateur mycologist R Gordon Wasson journeyed around Mexico and South America in a quest for magic mushrooms and spent a 'wondrous' evening after ingesting them in a shamanic ritual. He was later disgusted by the popularity and misuse of his 'discovery'.