 By the fifth century, Augustine of Hippo wrote in "On Christian Doctrine" that "perpetual peace is indicated by the olive branch ("oleae ramusculo") which the dove brought with it when it returned to the ark".In the earliest Christian art, the dove represented the peace of the soul rather than civil peace, but from the third century it began to appear in depictions of conflict in the Old Testament, such as Noah and the Ark, and in the Apocrypha, such as Daniel and the lions, the three young men in the furnace, and Susannah and the Elders.Before the Peace of Constantine (313 AD), in which Rome ceased its persecution of Christians following Constantine's conversion, Noah was normally shown in an attitude of prayer, a dove with an olive branch flying toward him or alighting on his outstretched hand.