The thesis of this work is that two formations are implicit in the text written by brazilian historian João Capistrano de Abreu: that of brazilian nationality and that of Capistrano himself as a modern historian. The demonstration is done by reading Capistrano s texts - especially that written in the beggining of the 1880 s, when it became clear his option for history as a intellectual field, and the year 1907, when Capítulos de História Colonial, considered his main work, were published. The reading of those texts let one identify basic characteristics of modern concept of history, as the critical of documents and the construction of a narrative capable of organizing the selected documents. The plot of brazilian nationality formation is the axis presumed by his writings. The subject is approached by exploring a triple dialog of Capistrano with his predecessors (part I), with his contemporaries (part II) and with himself (part III).