The thesis is a performative and sensuous study based on pre-iconographic descriptions of the formal features in the ceiling paintings The Triumph of the Name of Jesus (1674-1679) by Giovanni Battista Gaulli (called Baciccio, 1639-1709) in Il Gesù, Rome and Glorification of Sant'Ignazio (1685-1694) by Andrea Pozzo (1642-1709) in Sant'Ignazio, Rome.  By tracing effects likely perceived by different visitors through eyesight and the movement in the room, the aim is to suggest why these artworks are perceived as powerful. The results show that the power of the illusion in both paintings lie in the questioning of elements a visitor will know devoid of iconography or theological understanding of the narrative. Through elements a visitor will recognize and have bodily and sensuous experience of, different features will make the visitor question reality related to painted fiction. This experience and how it affects a visitor is why the artworks hold a central place in the art historical view on the Baroque, and further, Jesuit Style. The method for this analysis is pre-iconographic descriptions of all the figures in the vaulted naves, that are analyzed by the author using performative theory and a sensuous perspective as the theoretical framework. The research question for the thesis is: How is a visitor affected by the formal features in "The Triumph of the Name of Jesus" by Giovanni Battista Gaulli and "Glorification of Sant'Ignazio" by Andrea Pozzo?