Italian mystic, theologian, biblical commentator, philosopher of history, and founder of the monastic order of San Giovanni in Fiore. He developed a philosophy of history according to which history develops in three ages of increasing spirituality: the ages of the Father, the Son, and the Holy Spirit.

The known facts regarding the life of Joachim of Fiore are few. Legends about his parentage and youth are of little historical significance, but from an autobiographical reference it seems certain that he went on a pilgrimage to the Holy Land that reputedly had an effect on his conversion to the religious life. He became a Cistercian monk at Sambucina and in 1177 abbot of Corazzo (Sicily). About 1191 he broke away from the distracting duties of administration and retired into the mountains to follow the contemplative life. Although claimed as a fugitive by the Cistercians, Joachim was allowed by Pope Celestine III to form the disciples who gathered around him at San Giovanni in Fiore (a town located in present-day Cosenza province in Calabria) into the Order of San Giovanni in Fiore in 1196.

Far more significant is the evidence for the inner development of a man who came to believe that spiritual understanding would be given to one who wrestled with the “letter” of the Scriptures to get at the “spirit.” Three moments of special illumination are indicated, but the first is only known in legendary form, connected with either his pilgrimage or his novitiate at Sambucina. The second, recorded by himself, took place one Easter eve, after a period of frustrated study of the biblical book of Revelation when he felt himself “imprisoned” by difficulties. In the midnight silence, suddenly his mind was flooded with clarity and his understanding released from prison. The third was an experience at Pentecost, when, after a time of agonizing doubt on the doctrine of the Trinity, Joachim had a vision of a psaltery with 10 strings, in a triangular form, that clarified the mystery through a visual symbol and called forth paeans of praise from him. He expresses this experience of illumination given after mental striving in terms of the city seen intermittently by the approaching pilgrim or of the spirit breaking through the hard rind of the letter.

He was summoned by Pope Lucius III in 1184 and urged to press on with the biblical exegesis he had begun. This probably refers to the Liber concordie Novi ac Veteris Testamenti (“Book of Harmony of the New and Old Testaments”), in which Joachim worked out his philosophy of history, primarily in a pattern of “twos”—the concords between the two great dispensations (or Testaments) of history, the Old and the New. But already Joachim's spiritual experience was creating in his mind his truly original “pattern of threes.” If the spiritualis intellectus springs from the letter of the Old and New Testaments, then history itself must culminate in a final age of the spirit that proceeds from both the previous ages. Thus was born his trinitarian philosophy of history in which the three Persons are, as it were, built into the time structure in the three ages or status of the Father, Son, and Holy Spirit.

The third status was to be won by the church only after arduous pilgrimage and great tribulation, like the Israelites marching through the wilderness and crossing the Jordan River into the Promised Land. As guides through this crucial stage, Joachim prophesied the advent of two new orders of spiritual men, one of hermits to agonize for the world on the mountaintop and one a mediating order to lead men on to the new spiritual plane. Although the third age belongs par excellence to contemplatives, secular clergy and laymen are not shut out of it. In a strange diagram, a “ground plan” of the New Jerusalem, various categories of monks are grouped around the seat of God, but below, secular clergy and tertiaries (lay members) live according to their rule.

In the Expositio in Apocalypsim (“Exposition of the Apocalypse”), Joachim seeks to probe the imminent crisis of evil, as pictured in the apocalyptic symbols of Antichrist, and the life of the spirit to follow. His third main work, the Psalterium decem chordarum (“Psaltery of Ten Strings”), expounds his doctrine of the Trinity through the symbol of his vision of the 10-stringed psaltery. Here and in a lost tract he attacked the doctrine of “quaternity” (an overemphasis on the “one essence” of the Godhead that seems to separate it from the three Persons of the Trinity and so create a fourth), which he attributed to Peter Lombard, a 12th-century theologian. Besides this trilogy, written concurrently, Joachim left minor tracts and one uncompleted major work, the Tractatus super quattuor Evangelia (“Treatise on the Four Gospels”).

Joachim was a poet and artist. His lyricism breaks through the biblical exegesis that he chose as his medium and the turgid Latin of his style. Above all, his visual imagination is expressed in the unique Liber figurarum (“Book of Figures”; discovered in 1937), a book of drawings and figures thought to be a genuine work by most Joachim scholars today. Here his vision of the culminating age of history is embodied in trees that flower and bear fruit luxuriantly at the top; his doctrine of the Trinity is expressed in remarkable geometric figures; his kaleidoscopic vision fuses images in some strange shapes, such as the tree that becomes an eagle, which may have influenced Dante. Joachim's figures probably carried his ideas in exciting and popular form far more widely than his indigestible writings.

In his lifetime Joachim was acclaimed as a prophet, gifted with divine illumination, and this is how he was seen by the first chroniclers after his death. The condemnation of his tract against Peter Lombard by the fourth Lateran Council in 1215 dimmed his reputation for a time, but the appearance of the Franciscan and Dominican mendicant orders, hailed as Joachim's new spiritual men, reestablished him as a prophet. The Spiritual Franciscans at mid-13th century and various other friars, monks, and sects down to the 16th century appropriated his prophecy of a third age. But Joachim has always had a double reputation, as saint and as heretic, for cautious Christian thinkers and leaders have seen his writings as highly dangerous. The debate as to whether he was orthodox or heretic continues today.