In 2005, Nelson Felix exhibited at the Imperial Paço in Rio de Janeiro the Trilogies of the Cross, of Time, of Emptiness which express the artist`s regard over his own work throughout twenty five years. The selected themes - time, void and cross - do not constitute autonomous approaches or researches, on the contrary, they intertwine and superpose. The works related to the cross establish a critic dialogue with the site-specific as part of the art expansion movement seizing the 60`s historical landscape, more specifically, Minimal Art and Land Art. Nelson Felix adopts the coordinates system and considers the displacement referred to the ecliptic like strategies to overcome the composition, converting them in elements that structure his poetics. Thus, the sites and the works absorb localization parameters, data that refers to an incommensurable order that escapes to our perception. The question of time presents itself through the complex texture that includes, beyond scientific data and technological artifacts, the symbolic meanings of matter and the study of human anatomy and ancestral cultures resulting, sometimes, in strange hybrid forms that resists to an easy comprehension, but emblematically represents the work as a whole. The nature is taken like an experimental field and constitutes the creative activity but not the object, constantly ephemeral, that remains. The research considers the singular way that Nelson Felix articulates the questions related with the tradition and the expanded field of sculpture, associating the procedures and the symbolic references to the themes: cross, time and emptiness. The Trilogies format has oriented the structure of the dissertation considering the intrinsic logic of its arrangements.