Seeking to come closer to comprehension of the nature of social transformations, the author of the article reviews historical types, structures, varieties of knowledge; he especially distinguishes basic and "peripheral" (free) knowledge. A highly efficient cognitive method is described, one which consists in the arousing of sense of the interesting. A typology of the interesting is offered (the interesting as the rare, as the enigmatic, as a system), as well as its social projection presented: nets of the interesting as conglomerations of individuals possessing a distributed resource (their common property). Such nets are exactly described, with materials of European history being involved in the description.