Encyclopaedia Britannica:
Catalan mystic and poet whose writings helped to develop the Romance Catalan language and widely influenced Neo-Platonic mysticism throughout mediaeval and 17th century Europe. He is best known in the history of ideas as the inventor or an art of finding truth that was primarily intended to support the Roman Catholic faith in missionary work but was also designed to unify all branches of knowledge...

Llull at the age of 30 experienced mystical visions of Christ on the Cross, after which he abandoned courtly life and devoted himself to missionary work. Influenced by the pacifist spirituality of St. Francis of Assisi, he traveled throughout North Africa and Asia Minor attempting to convert Muslims to Christianity.

About 1272, after another mystical experience on Majorca's Mount Randa in which Llull related seeing the whole universe reflecting the divine attributes, he conceived of reducing all knowledge to first principles and determining their convergent point of unity. Borrowing certain tenets from the 11th century Scholastic theologian Anselm of Canterbury, he wrote his principal work; this is collectively known as the Ars magna and includes the treatises Arbor scientiae and Liber de ascensu et descensu intellectus. Llull attempted to place Christian apologetics on the level of rational discussion, mainly to meet the needs of disputation with the Muslims. Llull used logic and complex mechanical techniques involving symbolic notation and combinatory diagrams to relate all forms of knowledge, including theology, philosophy and the natural sciences as analogues of one another and as manifestations of the Godhead in the universe. Llull thus used original logical methods in an attempt to prove the dogmas of Christian theology. The Ars Magna's apologetic applications receded into the background after Llull's death, and it was as a universal system and compendium of knowledge that the Ars remained influential...

Llull devoted his life to the spread of his Ars and attempted to interest rulers and popes in his projects. King James II of Aragon was persuaded to establish a school at Majorca for the study of Oriental languages so that the Ars could be disseminated throughout the Islamic world...

Llull was stoned in North Africa at Bejaïa or Tunis and died a martyr at sea before reaching Majorca, where he was buried. Charges of confusing faith with reason led to the condemnation of Llull's teaching by Pope Gregory XI in 1376. In the 19th century, however, the Roman Catholic Church showed more sympathetic interest and approved of his veneration. Current interest centres on his mystical writings, particularly The Book of the Lover and the Beloved. In Catalan culture his allegorical novels Blanquerna and Felix enjoy wide popularity.
Llull's Ars Magna was read with interest by Gottfried Leibniz, and inspired his Calculus Ratiocinator. Certain computer scientists now recognize in Llull's system the beginnings of their own discipline.

The Llullian Arts website hosts a wealth of information about this great mystic, writer, apostle, philosopher and martyr, including a series of twelve miniatures from an illuminated vita. Click on each of the images below to see it larger at the source, and to read the transcribed or translated text using a clever mouseover function:

Selected pages from a 1501 printed edition of the Ars Magna: