"Why doesn't all this information-processing go on "in the dark", free of any inner feel? ...We know that conscious experience does arise when these functions are performed, but the very fact that it arises is the central mystery. There is an explanatory gap [a term due to J. Levine, "Materialism and qualia: The explanatory gap" Pacific Philosophical Quarterly 64:354-61, 1983] between the functions and experience, and we need an explanatory bridge to cross it."