Neuroscientific research shows significant differences between the two hemispheres of the brain at the neuropsychological, anatomical, and physiological levels. This matters because human consciousness is mediated through the brain's bi-hemispheric structure. In The master and his emissary: The divided brain and the making of the western world (2009), Iain McGilchrist builds on Friedrich Nietzsche's reference to Apollonian and Dionysian impulses within human intellectual history, showing two dichotomous styles of thought (and perceptual/experiential realities constructed from them) battling for dominance. Neuroscientific insights can be applied to the writing of early Christian theologian Irenaeus of Lyons, whose theocentric understanding of the human person emphasizes God's total transcendence over all phenomena: God is the only reality, the only thing that really is, and over against God, called into existence out of nothingness by God, poised over nothingness, is everything that God creates. God's complete transcendence paradoxically implies radical immanence and closeness to us.