Alphonsus Maria de Liguori CSsR (27 September 1696 – 1 August 1787) was an Italian Catholic bishop and saint, as well as a spiritual writer, composer, musician, artist, poet, lawyer, scholastic philosopher, and theologian.

A prolific writer, he published nine editions of his Moral Theology in his lifetime, in addition to other devotional and ascetic works and letters.

He was the eldest of seven children of Giuseppe Liguori, a naval officer and Captain of the Royal Galleys, and Anna Maria Caterina Cavalieri.

Two days after he was born, he was baptized at the Church of Our Lady the Virgin as Alphonsus Mary Anthony John Cosmas Damian Michael Gaspard de' Liguori.

In 1731, while he was ministering to earthquake victims in the town of Foggia, Alphonsus said he had a vision of the Virgin Mother in the appearance of a young girl of 13 or 14, wearing a white veil.

They also fought Jansenism, a heresy that preached an excessive moral rigorism: "the penitents should be treated as souls to be saved rather than as criminals to be punished".

In 1732, while he was staying at the Convent of the Consolation, one of his order's houses in the small city of Deliceto in the province of Foggia in Southeastern Italy, Liguori wrote the Italian carol "Tu scendi dalle stelle" ("From Starry Skies Descending") in the musical style of a pastorale.

The version with Italian lyrics was based on his original song written in Neapolitan, which began Quanno nascette Ninno ("When the child was born").

He suspended those priests who celebrated Mass in less than 15 minutes and sold his carriage and episcopal ring to give the money to the poor.

In the last years of his life, he suffered a painful sickness and bitter persecution from his fellow priests, who dismissed him from the Congregation that he had founded.

[5] By May 1775, Alphonus was "deaf, blind, and laden with so many infirmities, that he has no longer even the appearance of a man", and his resignation was accepted by the recently crowned Pope Pius VI.

He was named the patron of confessors and moral theologians by Pope Pius XII on 26 April 1950, who subsequently wrote of him in the encyclical Haurietis aquas.

In bestowing the title of "Prince of Moral Theologians", the church also gave the "unprecedented honour she paid to the Saint in her Decree of 22 July 1831, which allows confessors to follow any of St. Alphonsus's own opinions without weighing the reasons on which they were based".

His best-known musical work is his Christmas hymn Quanno Nascetti Ninno, later translated into Italian by Pope Pius IX as Tu scendi dalle stelle ("From Starry Skies Thou Comest").

His masterpiece was The Moral Theology (1748), which was approved by the Pope himself[5] and was born of Liguori's pastoral experience, his ability to respond to the practical questions posed by the faithful and his contact with their everyday problems.