His opening chapter deals with the pre-socratic philosophers of 6th century BC Greece. In discussing the pre-socratics, he mentions their belief in monism. From Wikipedia:
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.In Step aside Edward Gibbon I mention our collective inclination to seek monocausal explanations to complex systems. So, is this tendency simply a biological circumstance of our DNA which was first articulated by the pre-socratics or is it that the pre-socratics have an enduring appeal even 2,500 years later. It has to be one or the other, doesn't it? Heh.