"Once we differentiate, differentiation becomes the denial of identity," Korzybski wrote in "Science and Sanity". "Once we discriminate among the objective and verbal levels, we learn 'silence' on the unspeakable objective levels, and so introduce a most beneficial neurological 'delay'—engage the cortex to perform its natural function." British-American philosopher Max Black, an influential critic of general semantics, called this neurological delay the "central aim" of general semantics training, "so that in responding to verbal or nonverbal stimuli, we are aware of what it is that we are doing".