Guillaume Courtet was born in 1589 or 1590 the little town of Sérignan (just inland from the coast on the Gulf of Lion) in Languedoc in the Kingdom of France, under the ecclesiastical administration of the Diocese of Béziers.

[4] His family, however, were fairly prosperous and prominent burghers, his father’s name is recorded in civic documents as holding the role of "second consul" in local government, and Guillaume enjoyed a first rate education.

Sometime around his mothers death he began studies at the Jesuit school in Béziers, now Lycée Henri-IV, where he received a solid humanist education.

[4] It was probably here that his early vocation to the missions in the Far East also germinated as stories of 1597 martyrdoms of Paul Miki and his companions spread through the institutions of the Society of Jesus.

[4] At the age of 15 he left Béziers to continue studies at the University of Toulouse in scripture and scholastic philosophy and theology in preparation for an ecclesiastical career.

As well as natural focus on Aquinas, Courtet also drew great inspiration from the strict monastic ideals of Sébastien Michaëlis who had been prior of Toulouse and was responsible for a widespread reform of the Dominican order across France, part of the Dominican response to wider reforms in religious life following the Council of Trent.

[4] In 1624 he was elected superior of the famous Dominican Priory at Avignon,[4] the first residence of the popes in the city during the early 14th century before the construction of the Palais des Papes.

[4] In 1626, Courtet was appointed "commissioner" of the Order of Preachers in Northern Europe with a difficult mission of spreading Michaëlis' reform of the monastic life of the friars in priories.

These reforms were focused on poverty in the cell and wider prioral complex, on fasting and abstinence, on a rigorous devotion to the Liturgy of the Hours, and on silent meditation.

[4] During this Courtet was also active in the diplomatic field of the Thirty Years' War and was commended by the French statesman Cardinal Richelieu.

He also became confessor to the French Ambassador and spiritual director to the Queen of Spain (Isabelle Bourbon, daughter of Henry IV).

It is probable that he and his companions were directly responding to the many calls for priests that reached Manila from the 200,000 strong Kakure Kirishitan community.

In the evening on Michaelmas Day (29 September) 1637, he was removed from the tsurushi pit and beheaded along with the others who hadn’t already died from blood loss.

[5] A Portuguese Sailor witnessed the incident and provided the Dominicans of Manila with a record of the martyrs last words including Courtet’s.