Pope Saint Hyginus was bishop of Rome from about 138 to about 140. He was born in Athens, Greece at an unknown date. During his papacy, he determined the different prerogatives of the clergy, and defined the grades of the ecclesiastical hierarchy. He also decreed that all churches be consecrated. He succeeded Pope Telesphorus who, according to Eusebius, died during the first year of the reign of the Emperor Antoninus Pius – in 138 or 139, therefore. But the chronology of these bishops of Rome cannot be determined with any degree of exactitude by the help of the authorities at our disposal today.