This paper aims at presenting the processes/mechanisms which characterize the emergence of different uses of the expression "É QUE", correlating its path linguistic change via grammaticalization of language metafunctions. This investigation diachronically analyses sampling data of written texts in Portuguese from the Twelfth to the Twentieth Century. The empirical results seem to prove the unidirectional trajectory Object/Space > Text hypothesis, resulting from the reanalysis of the original Fourteenth-century use of "é o que" to "É QUE". In terms of the language metafunctions, the trajectory of change in meaning is: Ideational (concrete) > Textual (discursive textual) > Interperson al (epistemic).
grammaticalization; É QUE; Language metafunctions; modality
