The Big Question: What is transcendental meditation, and is it the cure for society's ills?

Why are we asking this now?

Film director David Lynch and Sixties pop star Donovan have teamed up to launch a campaign to encourage children to meditate in school. In a series of talks , the pair will promote the technique of transcendental meditation practised by the Maharishi Mahesh Yogi and popularised by the Beatles 40 years ago.Another TM convert to have just emerged is Joaquim Chissano, the former president of Mozambique, who has been honoured with the Achievement in African Leadership award.

Has David Lynch done this before?

Yes. Lynch is reported to have persuaded 20,000 US pupils to take twice daily transcendental meditation lessons with their teachers. He has also donated millions to the David Lynch Foundation for Consciousness-Based Education. He said: "The technique of transcendental meditation has seen a drop in stabbings, violence, depressions, suicides and the use of illegal drugs in some of the worst schools in the US you can imagine." Lynch has also spoken of the benefits he has gained from TM: "When I started meditating I had a real anger in me, and I would take this out on my first wife. Two weeks after I started meditating, this anger lifted."

What does Donovan say about TM?

He claims it is the secret of his success as a musician. Last year the Scots-born troubadour, famous for hits such as "Mellow Yellow" and "Jennifer Juniper", said he was planning a world tour to reawaken people to the mind-expanding wonders of meditation. "I had all the western trouble of the psyche: anxiety, anger, stress and fear which all cause illness. Over the past 40 years I have experienced the way this system has absolute healing benefits."

How many people practise TM, and what does it involve?

About 6 million people worldwide, according to the official TM website. The technique involves a form of concentrated attention in which the mind is turned inward and focused on a single point of reference. This is achieved by uttering the mantra, a word given to the student during the initiation ceremony which is chanted silently over and over. The aim is to empty the mind of thoughts, feelings and fantasies, not by blocking their intrusion, which is impossible, but by observing them as they intrude and then always returning to the central task of attending to the mantra. In this way a state of inner peace is achieved.

With practice, it is said, the mind can transcend thought, is no longer bound by feelings or fantasies, and experiences "awareness of itself alone." Hence "transcendental" meditation.

Is there evidence that it is beneficial?

Yes. Scores of scientific studies have been published since the 1970s, a number of which have shown benefits in lowering stress, blood pressure, cholesterol, smoking, drinking and anxiety. In 2005, the American Journal of Cardiology reported that among 202 patients with raised blood pressure who were followed for 18 years, those who practised TM had a 23 per cent lower death rate. In 2006, a study in Archives of Internal Medicine found patients who practised the technique for 16 weeks had improved blood pressure, insulin resistance and nervous system. The National Institutes of Health in the US has found that people practising meditation have lower breathing and heart rate yet "higher EEG coherence" indicating greater concentration and alertness. Long-term practitioners speak of an experience of "unboundedness."

Why was TM so popular in the 1960s?

It started with the Beatles. George Harrison had become intrigued by a sitar he had seen on the set of the film Help! and flew to India for lessons from the master, Ravi Shankar. His wife, Patti, who accompanied him, learnt of the Maharishi's work, who by then had spent a decade on the road promoting the technique around the globe in an effort to "spiritually regenerate the world". After the Harrisons' visit, the Maharishi travelled to Bangor in north Wales where he was visited by the Beatles, among other celebrities.

The Maharishi had already learnt that a few pop-star converts could help his crusade to raise the world's consciousness and later he invited Donovan to visit him in Los Angeles. Donovan was initiated a few days later. Later in 1968 he visited the Maharishi at his ashram in India with the Beatles, Mia Farrow and Mike Love of the Beach Boys – and a global movement was born.

Has it all been peaceand love since then?

No. John Lennon soon fell out with the Maharishi and wrote a a song "Sexy Sadie" about his allegedly materialistic ways. It did not dampen enthusiasm for the technique and in the 1970s, the Maharishi launched a "World Plan" to establish a teaching centre for each million of the world's population. He also founded a political party, The Natural Law Party, which fielded candidates in elections in several countries including the UK but is now mostly defunct.

Since 1990, the Maharishi has co-ordinated his global activities from his headquarters in Vlodrop, a town in the Netherlands. In 2005, he ordered his followers to stop teaching the technique in Britain in protest against Tony Blair's support for the US in the Iraq war and the British electorate's failure to unseat him at the general election. He said there was no point in wasting the "beautiful nectar" of TM on a "scorpion nation." The ban has since been lifted.

Is it expensive to learn TM?

A course costs £1,280 in the UK. This includes four consecutive days of instruction (90 minutes a day) with "as much follow-up as is required for the first three to six months." Whether that is expensive depends on the benefits it brings. Ozzy Osbourne thought it a waste of time. He said: "I tried TM but gave it up and smoked a joint instead."

Some TM teachers have become concerned about the cost and have left the organisation to offer instruction on their own. In the UK there are 80 official TM teaching centres. Instruction begins with a short ceremony and then the student learns and begins practising the technique.

Should we all bedoing it?

The Maharishi, now aged 90, would wish it so. He believes the spiritual wellbeing of the world would be transformed if everyone spent 20 minutes each day meditating.

So should children be encouraged to practise TM?

Yes...

* It helps reduce stress and anxiety and offers a way of dealing with unpleasant emotions

* Medical evidence shows it can lower blood pressure and cholesterol and benefit the heart

* Spending 20 minutes each day in quiet contemplation can increase peace in the world

No...

* It is mindless, time consuming and offers little benefit to those who cannot empty their minds

* Children should not be encouraged to indulge in quasi-religious practices until they are old enough to choose

* Greater benefits can be obtained by spending 20 minutes cycling, singing or reading