Castration is the process by which the sexual organs are removed, either by surgical or chemical means.
Followers of early Christianity considered castration an effective and acceptable way to counter the sinful desires of the flesh, meaning sexual arousal – based mainly on a reading from the Gospel of Matthew 19:12. Despite this, the first law of the First Council of Nicaea in 325 outlawed the practice of castration in the Roman Empire.
Lord Asriel mentions that castration proved useful to the Church because it kept young boys' voices from breaking once they reached puberty. This was beneficial to church music because women were not permitted to sing in churches. Opera composers wrote for castrato singers, and many famous pieces from this period, such as Mozart's Exultate Jubilate, now sung by sopranos were originally written for castrati.
However the Roman Catholic Church always considered castration to be mutilation and therefore a sin, and in the late 19th century it officially condemned the process.
Alessandro Moreschi was the last castrato to sing in the Sistine Chapel Choir.