William was born into a wealthy family at Vercelli in Italy. His parents died when he was a baby and he was raised by relatives. When William was fourteen, he went on a pilgrimage to Saintiago de Compostela in Spain. There he decided that he wanted to live only for God and became a hermit.
One day he worked a miracle where he healed a blind man, and suddenly found himself famous. William was too humble to be happy with the people's admiration. He really wanted to remain a hermit so that he could give all his attention to God. He went away to live alone on a high, wild mountain. No one would bother him now.
But even there he was not left alone. Men gathered around the saint and they built a monastery dedicated to the Blessed Virgin. His followers became monks at the monastery. Because of William's monastery, people named the mountain, the Mountain of the Virgin.
After a while, some of the monks began to complain that life at the monastery was too hard. They wanted better food and easier work. William would not relax the rule for himself. Instead, he chose a new head for the monks. Then he and five faithful followers set out to start another monastery, as strict as they were used to.
One of his companions was St. John of Mantua. Both William and John of Mantua were leaders and great friends, but they saw things differently. They soon realized that they would do better if they split up, each to start a monastery. John went east and William went west. They both did very well. In fact, both became saints.
Later, William became the advisor of King Roger I of Naples and the king helped St. William in return. William's good influence on the king made some evil men of the court very jealous. They tried to prove to the king that William was evil, that he was hiding behind a holy habit.
They sent a bad woman to tempt William to sin, but she failed. Instead she was sorry for what she had done. She repented and gave up her life of sin. St. William died on June 25, 1142 at Guglietto in Italy.