Petronax 1 was a citizen of Brixia ("civis Brexianae urbis"); moved by religious zeal he visited Rome and saw pope Gregory II (Gregorios 72) who sent him to Cassinum castrum (Monte Cassino), where he settled among the holy men already living there and was chosen by them as their leader ("qui eundem venerabilem virum Petronacem sibi seniorem statuerunt"); he was soon joined there by many monks, both nobles and men of lower rank, and became their abbot ("multorum ibi monachorum, nobilium et mediocrium, ad se concurrentium pater effectus"); this is dated as happening one hundred and ten years after the site had been destroyed (in 581, by the Lombards); they lived by the rule of St Benedict and repaired the old buildings, so that in time the restored monastery began to flourish; subsequently pope Zacharias (Zacharias 16) sent him aids for the monastery, including books of scripture and other useful items, among them the original manuscript of the rule of St Benedict, in the saint's own hand: Paul. Diac., Hist. Lang. VI 40.

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