In 1964, the Estonian composer Arvo Pärt was suffering from a creative crisis. As he neared his 30th year, he began to doubt the value of his music. Since graduating from the Tallinn Conservatory, he had composed almost entirely in the 12-tone technique pioneered by Arnold Schönberg. This work was not only criticised by the Soviet authorities, but also trapped Pärt in a creative cul-de-sac of shrill dissonance and derivative experimentalism. Looking for an escape, he started to work in collage, blending Bach’s Sarabande with his own compositions, which followed the same rhythm and tempo, but were harmonised in 10-note clusters. As he later explained: ‘I wanted to prove to myself how beautiful Bach’s music was, and how hateful mine was […] I was convinced that through this musical sacrifice I could gain a clearer vision of my own contradictions.’

Pärt was a modern composer. He could not merely copy the elegant harmonies and graceful restraint of the Baroque period. Nonetheless, the sound of Bach’s musical phrases being twisted and torn was an eloquent expression of how desperate his situation. A few years later, the crisis reached a peak with Credo, another collage piece that combined a mishmash of innovative styles (dodecaphony, sonorism, aleatory technique) with a reworking of Bach’s preludes and several fragments from Christian literature. When the Soviet authorities banned the piece – too musically adventurous, too spiritually traditional – the composer withdrew from public attention into a near-decade of silence.

With Credo, Pärt bid farewell to High Modernism. ‘It was as though I had bought myself freedom, but at the cost of renouncing everything and being left completely naked.’ As his biographer Paul Hillier explained, ‘he had reached a position of complete despair, in which the composition of music appeared to be the most futile of gestures, and he lacked the musical faith and willpower to write even a single note’. Nonetheless, with its settings of liturgical texts and its attempt to blend competing voices, Credo marked the path of Pärt’s future work. And that work would eventually make him one of the most respected classical composers of the 20th and 21st centuries.

This year, Pärt turns 90. Although the composer has stopped writing pieces and withdrawn from public life, the enthusiasm for his music has never been higher. At the Proms in July, the Estonian Philharmonic Chamber Choir gave a special late-night recital in celebration. Throughout the autumn, there are performances taking place at the Barbican and the Wigmore Hall, not to mention Liverpool, Manchester, and Oxford. His sound is familiar to many who otherwise have little interest in classical music, and Pärt often competes with John Williams for the title of most-performed contemporary composer. But, whereas Williams produces maximalist orchestral scores for blockbuster films (54 Academy Award nominations and counting), Pärt creates spiritually searching works of instrumental and choral music characterised by their profound austerity. Nonetheless, this stripped-back simplicity and transporting beauty are beloved by performers and audiences alike. And both these qualities Pärt discovered during his years of silence.

As Harold Bloom has argued, most artists begin with imitation. However, the greatest artists are able to overcome their early influences to produce original work. This process if often painful, as it requires abandoning the methods that made possible their career, and even spending years in the creative wilderness. In the case of Pärt, he was rescued from despair by a recording of Gregorian Chant overheard in a record shop. As he later explained in Arvo Pärt in Conversation: ‘I discovered a world that I didn’t know, a world without harmony, without metre, without timbre, without instrumentation, without anything. At this moment it became clear to me which direction I had to follow, and a long journey began in my unconscious mind.’

Gregorian Chant is monophonic music, with a single melody designed around modes that set the pitch, the mood, the tone. Although attributed to the sixth-century pope, Gregory I, it actually dates from a few centuries later, when the relative stability of Carolingian rule allowed religious practice to standardise in Western Europe. It was used in the daily worship of religious communities throughout the Middle Ages: the simplicity of the music meant it could be sung by choirs of every level, from the smallest convent to the grandest cathedral. However, towards the end of this period, composers began bringing together multiple melodic lines to be sung at the same time, resulting in polyphonic chant – different voices reciting different melodies. During the Renaissance, the technical skill of the composer and the vocal range of the choir overtook the plain recitation of the text, and once local languages and musical traditions were incorporated into religious music, Gregorian chant became even less important.

However, in the mid-19th century, these chants were revived by the monks at Solesmes. A Benedictine abbey in north-west France, Solesmes was the first religious house established in France after the Revolution. Its founder, Prosper Guéranger, sent his monks to the great libraries of Europe to copy the oldest musical manuscripts they could find. Then they returned to the abbey’s scriptorium, transcribing the manuscripts into modern texts and adapting the stress-based scores into fixed forms of square notation. These were finally assembled into collections of Latin prayers and psalms used by monks to celebrate the daily services, which were soon approved by the Vatican and published in choir books known as the Liber Usualis.

Soon after hearing the chant, Pärt visited a Catholic church in Tallinn and received a copy of the Liber Usualis. ‘When I began to sing and to play these melodies’, he said, ‘I had the feeling that I was being given a blood transfusion.’ For the next seven years, Pärt listened to Early Music as much as possible, trying to learn all he could about the lives and beliefs of the monks who sung these chants, as well as their methods of musical transmission. He also filled thousands of pages with single-voiced melodies, trying to capture their essence: ‘What I wanted was only a simple musical line that lived and breathed inwardly, like those in the chants of distant epochs.’

Eventually, Pärt began to experiment with using two voices together and discovered his tintinnabuli style. Taken from the Latin for ‘little bell’, this stepwise compositional method consists of a first voice confined to a tonic triad, while a second voice provides a diatonic melody. It became the mathematical formulation behind the works of haunting bareness that Pärt composed in the second half of the 1970s: Für Alina, Spiegel im Spiegel and Cantus in Memoriam Benjamin Britten. Because the three notes of the triad come from a single chord – split into arpeggio form so that the separate notes create a bell-like chiming – they provide a sense of harmony for even the most dissonant note pairings. What’s more, the slowness of the tempo gives that dissonance a yearning quality, opening resonant spaces between each note to evoke a longing for resolution in the listener.

Performers talk about how Pärt’s tintinnabuli style is deceptively difficult. The sparseness of the scores means that, according to David James of the Hilliard Ensemble, the music cannot support too much forced emotion. Instead, performers must achieve a state of inner calm to convey the purity of the sound. ‘It has this ethereal quality,’ he explained. ‘I’ve described it as being naked, performing naked. You’ve got nowhere to hide.’ A technical challenge, but a psychological one too, reflecting the fact that Pärt’s breakthrough was equal parts musical and spiritual. And the religious significance of his melodic innovations comes from an unlikely source: an Orthodox monastery in a quiet corner of Essex.

Essex is not known for nurturing saints. Though medieval East Anglia attracted numerous holy men and women, in the centuries between the county acquired a more profane reputation. But in 2019 the Ecumenical Patriarch of Constantinople canonised a local named St Sophrony of Essex. The saint had been born in Moscow in the late 19th century, studied at the city’s prestigious art school, relocated to Paris because of his opposition to Marxism, and then abandoned art as he could not capture the divine in paint. Then, he joined the monks on Mount Athos, becoming a disciple to one of the most respected starets or spiritual teachers of the 20th century: Silouan the Athonite.

After Silouan’s death, Sophrony returned to Paris to publish a biography of his teacher, as well as several collections of the starets’ writings. Then, in 1958, he moved to Britain to found an Orthodox monastery in a former rectory near Tiptree, a 30-minute walk from the jam factory for which the town is best known. The monastery was named after John the Baptist, known as the forerunner in the Eastern Church, and most of its members were drawn from the Orthodox diaspora. Though Eastern monasticism had been suppressed behind the Iron Curtain, these exiled monks hoped to prepare the way for its rebirth in the Soviet states.

Arvo Pärt started visiting the monastery in the 1980s. He had converted to Orthodoxy midway through his creative crisis, and then relocated to Vienna at the beginning of that decade. Soon after his conversion, Pärt began reading Silouan’s writing and eventually decided that he must visit Essex to speak with Sophrony in person. The two men became close friends, the composer even buying a house a short drive from the monastery. And, when Sophrony was made a saint after his death, the chapel at the Arvo Pärt Centre in Estonia was renamed in his honour.

Pärt has claimed that he is ‘more at home in monasteries than in concert halls’, and his career has suggestive parallels with the saint: both of them displaced artists, trying to keep hold of their faith in the secular West. Furthermore, according to Pärt himself, Sophrony’s 500-page biography of Silouan is the key to understanding his own music. Orthodoxy has a special respect for mystical theology and the contemplative practices that bring direct experience of the divine. For Silouan, the longing for God was the foundation of belief, and if that longing was pure enough, the believer could acquire the ‘likeness’ of God or even complete union (theosis). However, this could only be achieved through the forgiveness of sin, which in turn required the removal of pride by sharing in Christ’s crucifixion.

Two of Pärt’s more recent pieces – Silouan’s Song, a 2006 composition for string orchestra, and a 2009 choral composition called Adam’s Lament – were based on texts attributed to the starets. The moving lines of the latter repeat his favourite themes – sin, love, and the distant hope of salvation – ‘The beasts and the birds were hushed in grief; / while Adam wept because peace and love were lost to all / men on account of his sin.’ Whereas the Western Church describes sins as a debt that must be atoned, the Eastern Church emphasises forgiveness as the process of becoming divine. This understanding of forgiveness is expressed in the music Pärt wrote after his near decade of silence: several times the composer has described the melodic voice as the human and the triadic voice as the divine – the former longing to find a lasting home in the latter. He has also described the tintinnabuli style in salvific terms: ‘the melodic line is our reality, our sins. But the other line is forgiving the sins.’

Pärt’s pieces share a remarkable fidelity to the language being set. They often follow a syllabic method (one note for each syllable), so that text and tune run in tandem. The vast majority of those compositions are based on religious passages, from Gospel extracts to a setting of the Canon of Repentance in Church Slavonic – the language used exclusively in Eastern liturgy. ‘The words write my music,’ the composer has claimed, and his reverential approach is partly explained by the fact Pärt believes the texts he is turning into music. These words are also the Word. ‘They are bound to universal truths’, he said about one setting of the Psalms, ‘purity, beauty, that ideal core to which each human being is bound.’

Exiled monks, Essex monasteries, mystical theology – these are not the conventional elements of musical success. At first glance, it seems strange that any contemporary composer would feel drawn towards Christianity in its most antiquated form. But, from an Orthodox perspective, the strictness of their worship is what makes it possible to approach the divine: by submitting to a set of unchanging practices, the self is cleansed of vanity, creating an empty space that can be filled with wonder. ‘Without discipline, freedom is very dangerous,’ Pärt’s wife Nora once explained, and in rejecting the anarchic liberty of High Modernism, the composer set himself free. Similarly, in embracing the fixed traditions of Orthodox liturgy, he discovered infinite possibilities within.

Pärt has always rejected the label ‘holy minimalist’ – the term used for a loose collection of late-20th century classical composers, who abandoned the avant-garde to write devotional pieces drawing on the traditions of Medieval and Renaissance music. It implies that his hard-won simplicity was a conjuring trick, pruning back his scores to achieve a serene but superficial emptiness. In fact, Pärt’s concentrated compositions contain more richness, more depth, than would be possible with many times more notes. Nonetheless, it’s revealing that the two most famous holy minimalists – Arvo Pärt and John Tavener – both converted to Orthodox Christianity. A third major member – the Polish composer Henryk Górecki – held firm to his Catholic faith during the long years of Soviet rule. Something about the traditional forms of Christian worship offered these composers a spiritual and cultural resource that was lacking in secular society.

In the case of Tavener and Pärt, their religious conversions took place during personal crises. At the same time, they marked a shift in style from exuberant modernism to an austere blending of the medieval and modern, the experimental and the liturgical. But, whereas Tavener’s compositions reach towards paradise, transporting the listener into the realm of the everlasting, for Pärt the sublime and the sorrowful are mingled much more closely. Often, they dance together and apart within a single musical phrase, placing the mortal in delicate tension with the divine.

The composer’s music makes no doctrinal demands on the listener, and many of Pärt’s fans know nothing of the spiritual struggle from which it was born. Instead, they respond to his tintinnabuli style because it contains both suffering and its antidote; the pain of living in a fallen world and the peace that is promised by forgiveness. It would be crude to claim that Pärt made classical music beautiful again, but he recognised that High Modernism could neither conjure a sense of wonder nor instil a sense of peace. And, by turning 20th-century compositions into prayers, the composer revived music’s unique ability to express the ineffable and touch the transcendent. In the process, he discovered millions of listeners who might otherwise have never engaged, and this is surely the secret of Pärt’s popularity: to make classical music sound sacred once more.