. ▁ ▁S acks ▁noted ▁in ▁a ▁ 2 0 0 1 ▁interview ▁that ▁severe ▁sh yn ess , ▁which ▁he ▁described ▁as ▁" a ▁disease ", ▁had ▁been ▁a ▁lif el ong ▁imped iment ▁to ▁his ▁personal ▁interactions . ▁He ▁believed ▁his ▁sh yn ess ▁stem med ▁from ▁his ▁pros op agn os ia , ▁popular ly ▁known ▁as ▁" face ▁blind ness ", ▁a ▁condition ▁that ▁he ▁studied ▁in ▁some ▁of ▁his ▁patients , ▁including ▁the ▁tit ular ▁man ▁from ▁his ▁work ▁The ▁Man ▁Who ▁M ist ook ▁His ▁W ife ▁for ▁a ▁Hat . ▁This ▁ne uro log ical ▁dis ability ▁of ▁his , ▁whose ▁sever ity ▁and ▁life - imp act s ▁S acks ▁did ▁not ▁fully ▁grasp ▁until ▁he ▁reached ▁middle ▁age , ▁even ▁prevent ed ▁him ▁from ▁recogn ising ▁his ▁own ▁reflection ▁in ▁mirror s . ▁S acks ' ▁el dest ▁brother ▁Marcus ▁also ▁had ▁pros op agn os ia . ▁ ▁S acks ▁sw am ▁almost ▁daily ▁for ▁most ▁of ▁his ▁life , ▁beginning ▁when ▁his ▁sw imming - ch ampion ▁father ▁started ▁him ▁sw imming ▁as ▁an ▁infant . ▁He ▁especially ▁became ▁public ly ▁well ▁known ▁for ▁sw imming ▁when ▁he ▁lived ▁in ▁the ▁City ▁Island ▁section ▁of ▁the ▁Bron x , ▁as ▁he ▁would ▁rout in ely ▁sw im ▁around ▁the ▁entire ▁island , ▁or ▁sw im ▁vast ▁distances ▁away ▁from ▁the ▁island ▁and ▁back . ▁ ▁Ill ness ▁and ▁death ▁S acks ▁under w ent ▁radiation ▁ther apy ▁in ▁ 2 0 0