He began to practice an ascetic life at the age of 20. He took to heart the saying of Jesus in Matthew: 'sell what you possess and give to the poor.' He therefore preached simplicity and the practise of poverty. Antonius withdrew for absolute solitude to a mountain by the Nile. Around 305 he emerged from his retreat to organize the monastic life of the hermits who imitated him.

The monastery (Der Mar Antonios) he built still stands in the desert between the Red Sea and the Nile. The monastic rule that bears Antonius name is still observed by Coptic monks.

The Life of Antony by Athanasius