In this text, some methodological possibilities for the study of the history of political ideas are discussed, considering the analysis of the process of flow of ideas and cultural appropriation.The political history in the transition to modernity at the turn of the XIXth to the XXst century is highlighted, in view of its singularity in the general process of political and existential experiences lived-out through the political activities of intellectuals and their cultural exchanges.The political and intellectual sociability of Joaquim Nabuco, and of historians who undertook a cultural and diplomatic movement in writing the history of relations between Brazil and Argentina and their former metropolis (Portugal and Spain) is focused through their reading practices and quoting of authors and books.