Canon 21
On the eunuchs who have been made such by others or those who cut off their natural parts themselves.
If someone has his natural parts cut off by a physician because of the sickness, or if he was castrated by the barbarians or some stupid people, but [othewise] is a virtuous man, the canon allows him to be promoted to the clerical office. If, however, someone being healthy thought that he can separate himself from the carnal passions not by the religious discipline and abstinence, but by cutting the body created by God, and castrated himself, we decree that he cannot be admitted to the clerical office. If he has already been promoted to the clergy, the ministry shall be forbidden to him, and he shall be deposed.
(trans. M. Szada)