Deformation and Revelation: Prerequisites for the Visual Miracle. Inácio Vieira’s Treatise on Optics.

Abstract

This article focuses on the contents of optics regarding image projection onto flat, curved, and composite surfaces and the metaphor of the visual miracle. This field, characterized by the Minim Jean François Niceron as perspective curieuse (1638) and consolidated under the term anamorphosis by the Jesuit Gaspar Schott in his Magia universalis naturae et artis (1657), sought to demonstrate that even what apparently transcends reason possesses a logical truth. Thus, and within a religious context, these techniques were instrumentalized by these intellectuals, as well as Athanasius Kircher and Emmanuel Maignan, for the fabrication of phantasmagorias that combined mathematical rationalism with theological mysticism, aiming to inflame faith.

Based on this framework, is proposed an examination of the geometric rudiments essential to the delineation of illusions intended both for the demonstration of the visual miracle, through anamorphosis, and for the perceptive transformation of space, through quadratura painting. To this end, the resonance of these contents is analysed in depth within the work of the Jesuit Inácio Vieira, specifically in his manuscripts on Optics, considering both the version in the National Library of Portugal (1714) and that of the National Library of Brazil (1719), whose circulation attests to the dissemination of this knowledge in overseas territories during the gold cycle.

More specifically, the research focuses on Part 3 of the treatise, entitled 'On the deceptions and disillusions of sight' (Dos enganos e desenganos da vista), which includes a detailed analysis of the geometric properties of visual rays, optical illusions, and curiosities. Vieira distinguishes physical optics (the study of the visual organ) from geometric optics (perspective), treating the visual line as a mathematical entity capable of simulating and manipulating reality. The deception of sight is defined by him not as a sensory error, but as a discrepancy or deformity between the visual image painted on the retina and the actual object, providing the foundation for understanding to enlighten reason.

The applied methodology is based on a comparative analysis of Vieira’s manuscripts with reference to European treatise tradition, such as Dechales, Niceron, and Pozzo. Through a commented reading of Vieira's text and the analytical redesign of his projective schemes, with particular focus on the radiant triangle (triângulo radiozo) and the mesoptic instrument of Kircher/Schott, the geometric and mechanical rudiments of image delineation and projection are decoded. The central objective is to clarify the deformation procedures that sustain the creation of illusions and the fabrication of the visual miracle in the Baroque context.

Inácio Vieira’s systematization reveals perspective as an instrument of creative ingenuity (engenho criador), freeing it from mere imitation of the natural to establish itself as a tool for transforming the perceived world. By providing procedures for the manipulation of the visual miracle, Vieira perpetuates a symbolic vision of the cosmos where the primacy of the senses over reason serves the designs of Baroque visual culture, becoming an essential document for understanding the circulation of scientific knowledge and its respective transfer to Luso-Brazilian artistic practice.