Neoplatonism:A philosophical school of thought that emerged in the 3rd century AD, which had a strong influence on Augustine's ideas. Neoplatonism emphasized the existence of a single, ultimate reality or 'the One' from which all other things derive.
Original Sin: The Christian doctrine that all human beings are born with a sinful nature, inherited from the first human beings, Adam and Eve, as a result of their disobedience to God.
Free Will:The ability of an individual to make choices and decisions without external coercion or constraint. Augustine's views on free will were influential in shaping the Christian understanding of human agency and responsibility.