Monism is the view that attributes oneness or singleness (Greek:μόνος) to a concept (e.g. existence). Substance monism is the philosophical view that a variety of existing things can be explained in terms of a single reality or substance. Another definition states that all existing things go back to a source that is distinct from them (e.g. in Neoplatonism everything is derived from The One). This is often termed priority monism, and is the view that only one thing is ontologically basic or prior to everything else.