 At his peak, he was a formidable tactician who could provide a stiff battle for the very best players, as his wins over Alexander Alekhine, José Raúl Capablanca, Efim Bogolyubov, Grigory Levenfish, Akiba Rubinstein, Rudolf Spielmann, and David Bronstein, among others, attest.His physical disability of being a deaf mute, and success at overcoming this in chess, is impressive.He was Jewish.