In reaction against Manicheism, Augustine in his thirties stressed both church authority and individual freedom. Without God's grace to rescue the fallen man, the right path could not be followed. In his sixties he developed his ideas further, stressing the need for authority to implant faith, which can be developed and consolidated by reason.‘Nature and grace’ examines Augustine's growing interest throughout his life in the theme of man's absolute need for grace. Augustine, it seems, thought that authentic Christianity was other-worldly, deriving its reference points and criteria from considerations beyond time and history. He did not believe, however, that human life was simply material in nature.