In 1860 he founded, together with his brother-in-law Moritz Lazarus, the Zeitschrift für Völkerpsychologie und Sprachwissenschaft, in which was established the new science of comparative ('folk') psychology.
În anul 1860 a fondat, împreună cu cumnatul său, Moritz Lazarus, Zeitschrift für Völkerpsychologie und Sprachwissenschaft, în care a pus bazele noii științe a psihologiei comparative („psihologia popoarelor”).