This article argues that the diffusion of concepts and theories from one culture or society to another requires the active engagement of a category of agents which I identify as ‘intellectual entrepreneurs’. Two historically contrasting cases of the transmission of ideas are examined in order to explain the processes whereby alien concepts are diffused across cultures. Foreign ideas and concepts that are successfully assimilated into a culture are neither automatically accepted nor externally imposed. Rather, knowledge flow succeeds on the basis of selection and transformation by local intellectual entrepreneurs who at the same time transform the receiving context to accommodate the modified foreign ideas. The activities of individuals, as intellectual entrepreneurs, are identified and discussed in order to indicate the processes through which alien concepts and theories are diffused into a receiving culture.