THE Benedictine abbot Aelfric of Eynsham (c.955-c.1010), as Michael Carter of English Heritage reminds us in his introduction to the current powerful exhibition with Sam Fogg (to 26 May), characterised life in medieval Europe and a harmonious society, thus: “Laboratores are those who labour for our living; oratores are those who pray to God for our peace; bellatores are those who battle to protect our towns and defend our land against invading armies.”

The Mayfair exhibition, brought together by Jana Gajdošová and Matthew Reeves, richly celebrates the lives of those who prayed, principally in monastic and conventual societies. Ceramics, stained glass, manuscripts, and sculpture, as well as precious metalwork and a remarkable survival of an Opus Anglicanum red velvet cope of the late 15th century, chart the growth of monasticism across Europe from the earliest traditions of Syria and Egypt.

The exhibition makes clear how monasticism constantly evolves, in response to the changes of society and the structures of the Church. In the 13th century, the Dominicans became known as a preaching order, following the example of their founder, the Castilian priest Dominic de Guzmán. Sam Fogg has a delicately inscribed Italian chalice (c.1530) commissioned by Daniel and Giacomina Portinari, which, unusually, has engraved figures, including Saints Dominic and Roch and the donors, on the hexafoil base.

The Franciscans with a Rule of Poverty spread just as rapidly as the Dominicans in urban areas. Francis of Assisi died at the age of 44 in October 1226, and, by the time he was canonised two years later (16 July 1228), images of him had circulated across central Italy and spread around the Continent wherever the Franciscans had gone.

The National Gallery exhibition opened on Coronation Day with il Poverello, in stark contrast to the pomp on view further down Whitehall in the Abbey. The nobleman’s son who rejected his inherited wealth has remained one of the most widely known of medieval saints. His life of abstinence, living in communion with Nature, speaks as strongly to the concerns of our own global community today as it did in earlier centuries. He is portrayed on the side of a pear-shaped lustreware jug from Umbria (c.1525), kneeling in prayer as the rays of Brother Sun shine down on him (Sam Fogg).

Little wonder that the current Pontiff should quote from his namesake’s Canticle of the Sun for his 2015 encyclical Laudato Si’. The hymn is cited in full, both in medieval Umbrian and in translation, in the opening pages of the catalogue.

The exhibition includes relics as well as the work of contemporary artists. In 1985, the 35-year-old Antony Gormley modelled himself for a naked body-cast that greets us. It is in lead and fibreglass (Tate) and based on the pose captured by Giovanni Bellini of the exultant saint. Saint Francis in the Desert is in the Frick Collection in New York and, sadly, not on show in Trafalgar Square. In May last year, Richard Long (b.1945) walked in the steps of the saint on Mount Subasio and in Assisi itself. Those familiar with his land art will know what to expect.

The earliest exhibit that may have come from the original furnishings of the Lower Church in the basilica at Assisi (consecrated in 1253) is a tempera painting on panel which measures 111.5 × 154.5cm. It is not now thought likely that this was the board on which the dead saint was ritually washed before burial, as was piously claimed in the 16th century.

In the central field, il santo stands, holding a red cross in his right hand and an open book in the crook of his left, allowing the wounds of the stigmata in his hands to be viewed. Around him, the Italo-Byzantine artist has depicted four posthumous miracles. By the 1250s, the saint’s reputation was widely promoted. His knotted girdle, hanging like a plumbline from his waist, has five knots.

© MUSEO DE BELLAS ARTES DE SEVILLABartolomé Esteban Murillo (1617- 82), St Francis Embracing the Crucified Christ (1668-69), on loan to the National Gallery from the Museum of Fine Arts, Seville

Another mid-13th-century panel, one of the great treasures of the Civic Museum in Pistoia, from the Franciscan church there, includes four miracle scenes, as well as four scenes from the saint’s life, among them that of the approval of the Rule by Innocent III, and his funeral. In the narrow decorative borders either side of the life-size saint, all but hidden, are painted busts of eight early Franciscan figures. Around the outer frame are empty oval recesses. Had these once held relics, as commonly developed in the 14th century in Siena for reliquary tabernacles?

A successful mission to England had established a province by the year of the saint’s death, and images appeared this side of the Channel at much the same date. One is the wall-painting at Doddington, Kent, is in the Parish Church of the Beheading of St John the Baptist. Another can be found here in the marginalia of the Chronica Maiora, the history of the world by Matthew Paris (Corpus Christi College, Cambridge).

These include scenes of Francis preaching to the birds after being rejected by his Roman audience and of his lying on the ground, his hands and his feet already marked by the stigmata with blood-red dots and splodges of colour. Paris can never have met Francis, but the alert face of an early English friar, Brother William, on the next page is characterised enough to suggest a portrait.

This scene on Mount Verna was developed by artists to represent the mystical Francis. From Dublin comes one of El Greco’s depictions of the scene that was painted in Seville c.1590-95. The grey-habited saint stands out against the deep-blue sky, looking up to the bright rift in the clouds from which the seraph had visited. We are left to contemplate his inner call in our own devotional meditation.

Michelangelo Merisi da Caravaggio, working at much the same time in Rome, invents his sensuous version. It was probably his first religious commission and daringly emphasises the close affinity of our spiritual and sexual natures. It was commissioned either by a wealthy Genoese banker who was resident in Rome or perhaps by the cardinal with whom Caravaggio lodged briefly; either patron would have treasured the picture as an intimation of Christ’s Passion.

 That painting (the Wadsworth Athenaeum, Hartford, Connecticut) seemingly later influenced the compositions of Bernini for his monument of the Blessed Ludovica Albertoni in the Roman church of S. Francesco in Ripa, Trastevere, and his sculpture of The Ecstasy of St Teresa of Ávila. Our own generation, obsessed with the body and ignorant of the soul, risks misunderstanding such works.

In the 17th century, the greater confidence of the Counter-Reformation and the resurgence of Catholic Christianity across the Continent inspired altarpieces that are more dramatic, presented almost as theatrically staged works for our devotion, as we, the prayerful spectator, watch the encounter between the man from Assisi and his God. Frans Pourbus (the Louvre) and Francisco Ribalta (1565-1628), painting in the 1620s, renew the invitation to those at the altar to explore such a relationship with God as the saint enjoyed four centuries earlier.

In 1651, the Capuchin church in Seville burned down. Bartolomé Murillo (1617-82), who became a lay Franciscan in 1662, was later invited to devise a new decorative cycle for the church’s side chapels and sanctuary. Although he largely followed the previous decorative scheme, he chose, instead of the stigmatisation, to paint the extraordinary scene of Christ embracing Francis from the cross.

The saint rests his right foot on the globe of the world as he reaches up to hold the Crucified, while Christ, his right hand freed from being nailed, wraps it around the saint’s shoulder. It is a commanding image that calls for our attention. Around 1620, Ribalta seems to have first devised this new iconography (for another Capuchin altarpiece in Valencia) to emphasise the enfolding of Christ’s love. Franciscans from the eastern Spanish port might have favoured the choice.

The fourth part of the exhibition concentrates on a Franciscan view of the natural world: two wolves were brought to the private view, and seemed as happy to be petted by Franciscans and whomever among the guests.

The Poor Clares and the ministry of St Clare of Assisi are also celebrated here. A small predella panel painted by Giovanni di Paolo (1403-82) shows her healing a child that has been rather less well treated by a wolf and who has been mauled, losing his arm.

At the intercession of the mother, the wolf is killed. I had hoped here to find a television set, as Pope Pius XII declared her patron saint of television in 1958, shortly before he died. That association derived from her having “seen” a mass as if projected on the wall of her cell when she was too ill to get out of bed and attend in person. In a stained-glass panel from Franconia (c.1410-20), she carries an unwieldy monstrance in her shrouded left hand, while, with her right, she catches up her robe to reveal her rich dress; she, like Francis, came from a noble family (Sam Fogg).

Also at Sam Fogg, a deliciously observed illumination from Lombardy shows Francis preaching in an octagonal stone pulpit within the compass of the historiated initial letter “O” (the Master of the Budapest Antiphonary, c.1444-50). The women sit on the ground, segregated from their menfolk, who crowded in behind them. Against a deep azurite sky with fluffy crowds sailing by, Francis points heavenward, while he looks compassionately on those grouped around him. It is an image both of the popularity that Francis brought to preaching the gospel and of the centrality of the gospel to the lives of all around.

Both exhibitions should hearten Christian visitors and inform others. Both are free, and the one at the National Gallery will serve parish groups admirably well. At the opening, the Cardinal Archbishop of Westminster spoke of Francis as a radical saint and observed how his appeal could be understood today, on the eve of the 800th anniversary of his death. He also recalled taking a youth pilgrimage to Assisi and finding young people readily engaged with and moved.

“Saint Francis of Assisi” is at the National Gallery, Trafalgar Square, London WC2, until 30 July. Phone 020 7747 2885. www.nationalgallery.org.uk

“Those Who Pray: Monastic Communities in Medieval Europe” is at Sam Fogg, 15a Clifford Street, London W1, until 26 May. Phone 020 7534 2100. www.samfogg.com