The CND is 50, and the organisation is commemorating its anniversary by encircling AWE at Aldermaston on Easter Monday, just as they did 50 years ago. A new book commemorates a half century of the campaign's enduring symbol, which according to its pacifist designer Gerald Holtom was based on the semaphore signals for N (nuclear) and D (disarmament).

Creativity is a mysterious process, unamenable to logical analysis. Much that appears to be original turns out to be an imaginative fusion of things half-remembered. So it may well have been with the peace symbol, which takes the form of a circle around an inverted version of a Norse symbol - yggdrasil, the 'world tree', or great ash at the centre of the universe.

An Ottawa Citizen review describes how Gerald Holtom asked a shop assistant what she thought of the symbol which was carried by the marchers on what he called 'lollipops'. She liked it, but wondered whether its drooping arms weren't "a bit depressing. Shouldn't peace be something to celebrate?" "He sort of altered his view in that moment," his nephew recalls. "He said, 'Yes, it should be a figure with the hands upwards outstretched'". From then on Holtom always drew the symbol upright.

In his hugely influential 'Book of signs' (first published in German in 1923 as 'Das zeichenbuch' and available on Google Books) Rudolf Koch uses the symbol to stand for a man who undergoes the 'vicissitudes of life'. On his death, the symbol is inverted (and known as the 'todesrune'). With this meaning the symbol was officially specified for the gravestones of SS officers. Gerald Holtom asked to have the symbol - in its upright form - on his gravestone in Kent. That wish was ignored by the letter-cutter.

In the runic alphabet a similar symbol to the yggdrasil is called algiz, (the elk) and is known as the rune of protection.

Opponents of CND referred to the logo as 'the chicken's foot' and Hopi Indians use a similar design, based on the footprint of a crane, as a symbol of tribal unification. It can also be thought of as an inverted or broken cross, like that used to crucify St Peter.

But the roots of the sign may well lie deep within all of us. As a Jungian archetype, it can be read as female genitalia. A sign for the ancient mother goddess, whose message of peace men so often ignore.

First they came for the Jews
and I did not speak out
because I was not a Jew.
Then they came for the Communists
and I did not speak out
because I was not a Communist.
Then they came for the trade unionists
and I did not speak out
because I was not a trade unionist.
Then they came for me
and there was no one left
to speak out for me.

Pastor Martin Niemöller

Rudolf Koch's symbols are available as a set of fonts issued by P22.

JS Bach is often cited as the greatest ever composer and the St Matthew Passion as his greatest work. Setting the text of Chapters 24-27 of St Matthew's Gospel, it tells the story of Christ's last days up to the crucifixion. First performed on Good Friday in 1727 in the Thomaskirche in Leipzig where Bach was Kapellmeister, it was not revived until around a century later, when the poet Goethe identified something of 'elemental significance' in the music. Both Mendelssohn and Vaughan Williams championed the Passion, the latter so fiercely that he would leave the platform glaring if anyone dared break his rule of absolutely no applause during or after the performance. This was three hours of music beyond all other music.

Tonight Reading Bach Choir and the City of London Chamber Players performed the work with such intensity that, between their arias, even the soloists seemed lost in its sublimity. Reading Town Hall, with its crisp acoustic and split choir seating, was perfect for the work's two orchestras and choirs. Taplow Boys' Choir sang beautifully from the balcony.

Three hours passed so easily. The St Matthew Passion is powerful musical drama, built around a framework of spare recitative narration by the tenor Evangelist (Christopher Watson). Choir soloists and six professionals took the principal roles and the choruses sing everyman. Picander's libretto bears fervent witness to the Passion story. With such poignant music, recent attempts at staging the work seem entirely superfluous.

The London Chamber Players played period instruments, achieving a highly articulate and refined performance that never overwhelmed the singers. Soprano Esther Levin and Counter-tenor Christopher Warwick sang with beautiful, relaxed simplicity the famously difficult duet with choral interventions 'So ist mein Jesus nun gefangen' - 'moon and light are extinguished by sorrow because my Jesus is captured'. This is followed by the challenging and dramatic chorus 'Sind Blitze, sind Donner', so popular in the 19th century that performances were frequently stopped by audiences demanding a reprise.

Against a single, shockingly dissonant diminished chord, the choir made an electrifying call for Barabbas and not Christ to be saved.  Counter-tenor Warwick again showed his quality in the difficult 'Ach Golgotha'. In a number of arias bass Robert MacDonald was gorgeously partnered by the agile musicianship of Viola da Gambist Charles Medlam.

The St Matthew Passion ends in sublime acceptance of the redemption offered by Christ's sacrifice. Caroline Trevor was mesmerising in No. 60 'Sehet, Jesus hat die Hand' (see Jesus, has his hand stretched out to grasp us). David Stuart sang Jesus with elegance and authority. He was almost transfigured as the dying Christ, in the moments when he lost his musical 'halo' - the glowing strings that accompany him in all other arias.

The choir sing 'When my heart is most full of fear, then snatch me from my fears by the power of your anguish and pain' and soon a final triumphant chorus celebrates Christ's victory 'Your grave... shall be...for the soul a resting place. In utmost bliss my eyes close in slumber there'.

Led by JanJoost van Elburg, Reading Bach Choir is achieving the highest musical standards. The fine English tradition of choral music-making is alive and well in the county town.

An article in Business Week attempts to get at the secret of Apple's design success. They say it boils down to developing ten genuinely different prototypes to a highly finished level, then letting two separate weekly meetings work away at them. One is briefed to only think 'blue sky', the other must address the practicalities. Ten ideas are then refined to three and finally to one.

I've been using a Toshiba laptop instead of my usual Apple one. It's like comparing a Lada with a Porsche. The Toshiba is all tacky, plastic ugliness compared to the Mac's seductive, clean lines, where everything is understated, integrated and in just the right place.

The Apple design process certainly works: Apple's laptop market share is up by 38% on last year, placing them 9th amongst the competition. The iPhone's iconic status as the must-have accessory for elite geeks so worries Google that they've launched a broadside against it. They claim their open source 'Android' programming environment will achieve more sales because it will be on many different manufacturers' phones.

OK, Apple's design process is thorough, and mildly innovative, but that's not it. They succeed because they have an uncompromising design-led vision - and they stick with it because they know the quality of their design has become an overriding factor in their customers' buying decisions.

Windows enthusiasts love to mock Apple and their lead designer Englishman Jonathan Ive CBE, whose early career famously included designing sanitaryware in London. Even in this apparently metrosexual age, there's bizarrely still something suspect about owning a computer that not only looks good but actually works as well. It seems real men not only don't eat quiche, they also don't do foofy computers that might (whisper it) call into question their owners' masculinity.

What chance of the Archbishop of Canterbury's support as pressure mounts on the Home Office to save 19-year-old gay Iranian Mehdi Kazemi from execution? At first the Home Office refused to re-consider his deportation, scheduled once the teenager is returned from hiding in Holland later this week.

Like around 4,000 gay Iranians executed by the Ayotollahs since they came to power in 1979, Kazemi faces death by hanging if he is returned to his country. There is no logic to the Home Office line that gay Iranians are safe as long as they are 'discreet' and that having once refused to grant him asylum, his case cannot be re-heard unless new facts emerge.

Kazemi claimed asylum in 2005 after his lover was executed in Tehran. After his asylum application was refused he fled to Holland where a court has decided he must be returned to Britain. He is currently on 'suicide watch'.

An appeal has been launched through the European Court of Human rights and more than 60 leading peers, including the Bishop of Liverpool, have signed a letter to the Home Office in his support.

In a moving statement to the Home Office he writes:

"The Iranian authorities have found out that I am a homosexual and they are looking for me. I can not stop my attraction towards men. This is something that I will have to live with the rest of my life. I was born like with feeling and can not change this fact... If I return to Iran I will be arrested and executed like Parham."

Will the Archbishop of Canterbury join them? Still bruised by his worthwhile contribution to the debate about Sharia, an urgent intervention by him would seem to be more than timely.

After this post was written the Home Office announced that after campaigning by his MP, Mehdi Kazemi had been granted five year's 'leave to remain' in the UK.

Which are the world's 50 greatest works of art? The Telegraph has published Martin Gayford's list. It's necessarily a fabulously subjective exercise, running all the way from an Egyptian sculpture of 2800 BC via van Eyck, Michelangelo and Velázquez to a sculpture by Donald Judd from 1982.

I was pleased to see the haunting Pompeii 'Villa of Mysteries' frescoes included, together with Giotto's breathtaking Scrovegni Chapel in Padua and Constable's 'Salisbury Cathedral from the Meadows'. 

But no Sistine chapel, or Turner 'Rain, Wind and Speed'! The Mona Lisa is knocked off her perch in favour of the same painter's 'Lady with an ermine' in Krakow. What about David's 'Death of Marat' with its superb handling of paint and poignant mythologising of the French Revolution? None of Ingres' portraits, with their relentless scrutiny of subject and no Delacroix or immaculate Vermeer interior? And what about the searing intensity of El Greco - and the homespun passion of Stanley Spencer?

And are the terracotta army and the Easter Island statues art works in the same way as the Jackson Pollock is thought to be? (I would have replaced it with something by Mark Rothko). Both the Easter Island statues and the terracotta army seem to me to be functional objects, created to fulfill a specific purpose, quite different to the making of an art work for its own sake.

I counted a respectable eight or so I've seen, but (with the help of some carbon offsetting), there's clearly plenty more prime art waiting to be discovered.

What is the 'real meaning' of art and what value should be placed on what is 'authentic' over the work of copyists?

At Christ Church Picture Gallery, Oxford, Curator Jacqueline Thalmann provided a fascinating introduction to the collection which is housed in a striking subterranean gallery from 1968 by Powell and Moya.

Although best-known for its collection of old master prints and drawings, over 200 paintings were bequeathed in 1765 by alumnus General John Guise, whose somewhat robust taste includes a Martrydom of St Lawrence by Tintoretto and a large and gruesome 'Butcher's shop' by Annibale Carracci (1560-1609) which since it was judged unsuitable for the contemplation of women hung in the College's kitchens for some 200 years.

Before the Renaissance, the best religious icons were those that faithfully copied from precedent. The essence of the divine could only be transmitted by the careful replication of visual convention. Any notion of artistic originality was irrelevant.

By Dürer's time the artist, not the subject, was the focus. His work – including a prominent monogram – was faithfully copied by a highly talented printmaker called Marcantonio Raimondi. In 1511 Dürer issued a devastating warning to anyone tempted to infringe what he was effectively asserting as his copyright: "Hold! You crafty ones, strangers to work, and pilferers of other men’s brains. Think not rashly to lay your thievish hands upon my works. Beware! Know you not that I have a grant from the most glorious Emperor Maximillian, that not one throughout the imperial dominion shall be allowed to print or sell fictitious imitations of these engravings? Listen! And bear in mind that if you do so, through spite or through covetousness, not only will your goods be confiscated, but your bodies also placed in mortal danger."

In what must be one of the first cases of its kind, Dürer succeeded in getting an injunction against Raimondi banning him from ever again misusing Dürer's trademark.

In common with the Carracci 'Butcher's shop', Anthony Van Dyck's 'Continence of Scipio' was revealed to be rich in multiple meanings. Van Dyck gave the famous Africa-conquering general filmstar looks, painting him into an epic scene reminiscent of Cecil B De Mille. Scipio's bright red cape billows as he nobly rejects the woman offered him in tribute. Her face is downcast and classically impassive whilst her betrothed, hand on heart, gazes beseechingly deep into the General's eyes.

The work was commissioned from the young Van Dyck by his court champion the Duke of Buckingham, whose stone capital, carved with two male faces, frames the scene. But the connections with Buckingham run deeper – Scipio can be read as James I, and the beseeching figure as Buckingham himself – James' 'favourite' and lover.

According to some 'queer historians' at least, gayness is also to be discovered in Dürer's life and work, not least in the woodcut 'Men's Bath' which features a prominent monogram (and a rather suggestive tap). Dürer's lifelong friend was a bisexual humanist called Willibald Pirckheimer. The humanist sent the artist drawings of the two of them in flagrante together. Consumed with jealousy, Mrs Dürer accused her husband of having a sexual relationship with the anagrammatic Pirckheimer.

The Daily Mail, like most of its stablemates, is gripped by another bout of Harry fever. The revelation that the carrot-top royal is soon to be an ex-air traffic controller in Afghanistan is accompanied by acres of perfectly posed photos of the pin-up prince on patrol with the Ghurkas. Tragic that for him it's "a dream come true" to take part in a ghastly conflict in a country that's been wrecked by a poisonous cocktail of religious extremism mixed up with centuries of outside interference.

What's more Harry hasn't "really had a shower for four days, haven't washed my clothes for a week and everything seems completely normal." The prospect of slightly whiffy Prince who has only had unreal showers lately doesn't entirely do it for me. Our obsession with endlessly rubber-necking young royals and now with their bathing habits strikes me as daft and intrusive.

The other day I was at a concert where I sat next to a young soldier the day after he got back from active duty in Iraq. After talking to him, and seeing him twitchy and alert to attack even in a concert hall in an English village, I have huge admiration for any young person brave enough to put their life on the line for their country.

It started with a low, distant rumble, somewhere to the north. It was 1am and I was wide awake and I thought I could hear rocks being ground together somewhere far, far away. I was wrong. The sound was not man-made - it came from deep down beneath the earth's surface: it was an ancient and utterly fundamental sound.

Then everything - me, my bed, the whole house - seemed to quiver slightly and it got faster and louder and ornaments were knocking and I knew this was my first experience of an earth tremor. After a few seconds the shaking died away. Then the only sound was the roar of water pouring over the weir and the call of a frightened blackbird, - 'pink, pink, pink', darting away in the darkness.

Apparently around 25 earthquakes are felt in the UK annually. At 5.2 on the Richter scale this was a one-in-30-year event, last matched by a 5.4 in Wales in 1984. It happened 15km beneath the earth's surface. The last time where was major earthquake activity at the epicentre, in Market Rasen in Lincolnshire over 100 miles from here, was in the 12th century. The seismologists say an old geological fault has opened up and may now become more active.

Congoo link

Web find of the month is a site devoted to complete reproductions of illuminated books. It includes Owen Jones' astonishing Grammar of Ornament (1856), a tour de force of nineteenth century letterpress and chromolithographic printing which has had an incalculable influence on artists and designers from the Art Nouveau to Gaudi in Barcelona.

Owen Jones' most influential book contains his own re-drawing on 'scientific' principles of over 2,000 decorative designs. The scope is vast: from designs created by 'savage tribes' to ornament from the ancient world, Arabia, China, India and Europe. The motifs presented range from intricate and highly elaborate high Renaissance manuscript illumination to apparently simple geometric tile designs from Moorish Spain and Persia.

A passion for the orient

Jones (1809-74) was an architect who became passionate about the superiority of non-European ornament after touring Turkey, Egypt, Sicily and Spain in 1831. Henry Cole, who founded the Victoria & Albert Museum, was one of his many collaborators.

Jones' passion for the near east found expression in his most significant work as an architect on the interior of Christ Church, Streatham. He was criticised for his  'excessive use' of Islamic motifs there.

Acclaimed for his decorations for the Great Exhibition in 1851, Jones worked for nine years on the publication of a lavish folio work, which exploited the capabilities of the relatively new and demanding process of chromolithography. He sold property to finance its publication, setting up his own press and training his own staff to produce it. He did not live to see it succeed commercially, and many copies were remaindered.

Besides including a historical survey and commentary on the many gorgeous full page colour illustrations, Jones developed a series of 37 'design propositions' which attempted to codify the construction of well-made ornament. For Jones: 'All ornament should be based on geometrical construction' And 'true beauty results from that repose which the mind feels when the eye, the intellect, and the affections, are satisfied from the absence of any want'. In his final chapter he advocated a new kind of architecture based on natural forms.

The rhythm of life

There is an enduring appeal in many of these stunning illustrations. They combine a remarkable and carefully constructed rhythmic intensity with a highly developed colour palette. Since the Modern Movement, architects and designers have associated ornament with the literally superficial, seeing it as a layer of irrelevant decoration that obscures the underlying nature of whatever it is applied to.

For me and I suspect for Jones, the desire to decorate is an integral part of human experience. His use of geometric reconstruction seems to link to metaphysical ideas of the golden section or 'divine proportion' which were taken up by Modern Movement architects such as Le Corbusier.

Good ornament is intrinsic to the very essence of things.

The Grammar of Ornament on CD-ROM for designers.

...Are all "bombers", according to a foolish seven year old in Holmfirth in Yorkshire. A woman of Pakistani origin, enjoying life with her mainly white neighbours, described hearing this said of her five year old by a stranger's child. It was soon after the July bombings in London. Can you blame her for moving from 'Last of the Summer Wine' country to urban Dewsbury?

Her voice is among many in an excellent series of programmes about Pakistan this week on Radio 4.

On Woman's Hour, an audience at Huddersfield University was in the main Pakistani. Most identified as British, but several wanted to know what had happened to 'British values'. Not just queuing and politeness, but tolerance and understanding.

Archbishop Rowan Williams has not seen much of that, after delivering a closely argued and liberal-minded talk on Islam and the British legal system. It was scheduled to be given in the ancient church of the crusading Knights Templar.

Williams begins by recognising a reallity - that sharia courts are operating in the UK now - and aligns Islam with other faiths such as Judaism that make rules for their followers that go beyond state law. Crucially he doesn't address the practicalities. What happens when religious law is in direct conflict with state law, as it would be if British sharia courts ever promoted the kind of sharia seen in Saudi Arabia? He blithely assumes people will be able to walk away from religious courts if they don't like them.

Bearded Asian men and wearers of the veil talked on Radio 4 about being stigmatised as religious extremists and potential terrorists. "Not everyone who wears a head-scarf is a potential Al-Qaeda member!" Young British Muslim women of Pakistani origin described how they walk a dizzying tightrope of mixed identities.

In spite of the support of the Bishop of Oxford, a mosque in Oxford is this week reviewing a non-Muslim's proposal to play the call to prayer to a  community that is not predominantly Muslim. The mosque's shortwave radio call to prayer is currently used by just 100 people. Many furious local objectors resent any form of religion proselytising to them.

The Royal United Services Institute condemn Britain's 'misplaced' policies on immigration and multiculturalism, creating opportunities for terrorists: "The UK presents itself as a target, as a fragmenting, post-Christian society". Sir Trevor Phillips, Head of the Commission for Racial Equality has been warning for years of the dangers of segregated communities. Nobel Laureate Amartya Sen defends liberty as more important than multiculturalism "the demands of cultural freedom include... resisting the automatic endorsement of past traditions"

Liberty's torch burns less brightly these days in the land of the free. The 'crusading' George W Bush this week used the July bombings as a justification for 'water-boarding' torture. Identity cards and incarceration without trial spark the fear that something similar is happening here.

The racist five year old in Holmfirth spoke from ignorance, because he had never met his Asian neighbours. In Huddersfield, Pakistani people complained that catchment area rules were preventing them from integrating their children with the children of non-Asians.

Freedom, religion and difference are hot topics - and for good reason. If ever there was a good time for British people of every race and religion to get together to decide what really matters to us - and what kind of society we want for the future - it is now.

Seven paintings, all of the same subject: a beautiful, almost naked youth, tied to a tree, in the throes of martyrdom. Five are almost identical versions of the same composition, from galleries as far away as Puerto Rico and New Zealand. All are uncompromising in their directness. The painting from Genoa inspired Wilde, Mishima and Pierre & Gilles. Stendahl claimed they so distracted the faithful that they had to be removed from churches.

The St Sebastians of the 'divine Guido' Reni (1575-1642) feature in an exhibition at the Dulwich Picture Gallery until May 11. It offers the public the chance to play an intriguing game of art historical 'spot the difference'. Which are 'real', which are copies? How much is the work of the master, and how much of his studio? Why are they such gay icons?

The Rome painting lacks the impact of its Genoese neighbour. The paintwork is softer, the face and body less defined. A third arrow has pierced the martyr's side and the feathers of another don't now clash with the Roman soldier in the background.

Standing in front of Reni's version from Genoa it is easy to see why it had such impact on Wilde: an athlete of classical build is indifferent to his wounds. Sacred: his boyish, asexual face, framed by his pinioned arms, gazes heavenward. Profane: his loincloth slips provocatively, emphasised by a partly turned hip.

Pierre & Gilles and Jarman also responded to this sultry mix of agony and ecstasy. Yukio Mishima had himself photographed as St Sebastian and in Confessions of a Mask the narrator discovers his sexuality because of a print of the painting.

Of the six versions of the (earlier?) composition, that from New Zealand is the most obviously different. The brushwork is far looser, there is less light - yet in spite of these differences, the current view is that it is by Reni himself. Comparing the others on view, they all seem as one.

The Dulwich's own St Sebastian was long thought to be a copy of the painting in the Prado, Madrid. Now restoration has revealed signs of pentimenti (second thoughts) that have enabled its attribution as Reni's own work.

For one critic Reni was self-consciously re-working notions of light, texture and atmosphere, the repeated composition a means to an end. Perhaps the explanation for so many versions is more prosaic: Reni wanted cash and welcomed requests for repeat business. He certainly went on to make other paintings of this middle-aged Roman soldier, the parton saint of sufferers of the plague, who met his final end only after his wounded body was dragged out of the cloaca maxima. Either way this Dulwich exhibition (which deserved much greater space) is fascinating.

The exhibition is complemented by a catalogue which contains more art historical analysis than is usual. Also on show was 'The age of enlightenment: Beardsley, Dulac and their Contemporaries 1890-1930' - Beardsley's perfumed and obsessional exoticism providing another take on image making.

Comprehensive Survey of images of St Sebastian

Review in the Independent