A pious child, getting up during the nights to pray and meditate. At age two he was given the choice of two of his father's books - and chose the one about saints. From age seven he daily recited the Little Office of the Blessed Virgin. He was always charitable, and even when young he worked with the poor, the abandoned, and the sick.
When he announced he wanted to join the preaching friars, his parents and friends tried to talk him out of it. But Ambrose had heard the call, and he joined the Dominicans in Siena, Italy in 1237 on his 17th birthday.
He studied in Paris, France, and Cologne, Germany with Saint Thomas Aquinas and Pope Blessed Innocent V under Saint Albert the Great. Taught in Cologne. Ambrose wanted to write, but saw the greatness of Saint Thomas, decided he could not match it, and devoted himself to preaching.
Worked on diplomatic missions for popes and secular rulers. Evangelized in Germany, France, and Italy; his preaching helped lead Blessed Franco of Siena to the solitary life. Mystic with a deep contemplative prayer life. He received ecstacies and visions, was known to levitate when preaching, and was seen circled in a mystic light in which flew bright birds.