Perhaps Cicero had been the unique orator among classical writers that gave especial attention to the relation between philosophy and rhetoric (wisdom and eloquence) linking these two disciplines once separated by Plato. Erasmus of Rotterdam, one of the most important humanists in sixteenth century, didn´t stay unaware of this tradition, but was also one of its most influent catalysts, pointing the necessity of vast knowledge for the dignity of human being. Erasmus consider that man at birth is still a substance rude, education is the major responsible for his moral and intellectual formation. Thus, the learning of studia humanitatis, whose defense is clearly in his early books, was a fundamental condition for complete realization of the ideals of Erasmus about renovation of Christianity, appearing of pure faith and educational reform. Considering the importance of rhetorical language in Erasmus works, we have chosen for the central purpose of this tesis the analysis of these two books that reveals the importance of classical precepts, that is, the union between res and verba in Ratio studii and De copia rerum ac verborum, respectively published in 1511 and 1512. In these two books Erasmus develops his interest on the purity of Latin, taught with ideas of Cicero and Quintilian, how to read and write the classics. Considered by many the first and the best educational manuals of Renaissance, these works are important not only for the correct apprehension of classical tongues, but also to the necessity of their imminent apprehension to the reader and correct understanding of the Scriptures in its purest state, the principal step to convince men about Christian philosophy.