Isaiah Boner (1400?-1471) was an Augustinian friar, a friend and confidant of saints, a professor of theology and a master of the religious and spiritual life.  He was known for his apostolic zeal and his life of austerity and prayer.

The exact year of his birth is not known.  He was born in Krakow, Poland.  He entered the Augustinian Order in Krakow in 1415 in his native city.

Isaiah was sent to study in Padua, where he earned a Lector's Degree in Theology and where he was ordained a Priest. Upon his return to Poland, he was assigned to teach Sacred Scripture and to oversee the formation of young friars.  He continued his study of Theology, and in 1443 was awarded a Master's Degree by Jaguelonica University in Krakow.

The Augustinian Order gave Isaiah several other responsibilities.  He was named Visitator of the Province of Bavaria.  In this capacity, he visited the Augustinian houses in Bavaria to ensure that each community there was remaining faithful to the monastic ideals of Augustine.  He was asked by the Prior General (world leader) to represent him and preside at the Provincial Chapter of Regensburg in 1452.

In addition, Isaiah taught Sacred Theology at the University of Krakow, where he was highly respected.

He died in 1471 and is buried on the grounds of the Augustinian monastery in Krakow.  After his death, people of the Krakow area honored Isaiah as a holy man.  They attributed numerous miracles and other graces to his intercession.  He was popularly called Blessed Isaiah, although this title was never confirmed by Church authorities in Rome.  In the 17th century, he was commonly listed as one of the "Saint Protectors" of Poland.  Pilgrims continue to visit his grave, drawn by his reputation for holiness.

The cause for his canonization was formally opened in 1994.  The diocesan investigation concluded in 1996, and the following year Rome approved the continuation of the process for Isaiah's beatification and canonization. Josef Sciberras, O.S.A., the Augustinian Postulator of Causes, oversees the progress of the cause.