 Many philosophers take perceiving X to be perceptually representing X. Intentional content on this reading is a semantic notion, and this suggests a linking principle tying conscious content to the brain: Perceptually representing X is based on neural representations of X. The “based on” locution hedges on the precise relation between neural contents and conscious contents, but a simple relation is identity: neural content is perceptual  content.[3]  This principle expresses a type of first-order representationalism about phenomenal content, a topic we return to in  section 5;  see also the entry on  representational theories of consciousness.  The principle explains specific consciousness by appeal to neural representational content.