For a better orientation in the blurred panorama of contemporary architecture, it may be adequate to insist on some basic issues that continue to configure the armature of authentic architecture: matter, light, structure and emotion. These issues are essential to architecture as a poetic of construction and a technique of the inhabiting. The specific approach on which Miguel Guitart focuses is the filter understood as tension between geometry, structure, gaze and light, and whose aim is to activate the architectural space in a profound and reflective way. Filters of gaze and light may be found in many cultures and under many guises, but they are always designed for a whole array of functions and made to measure for each region and for each person. The review of architectural filters presupposes the experience of the deep spatial emotion that they determine, the ascertainment and registering of the aforementioned invariants. The proposal of the author is to rediscover and deepen on these ideas of filtering, porosity and osmosis. The text wants to be an invitation to reintegrate them from timeless architecture into theory and practice of current architecture, as an analytical tool and a creative mechanism inherent to the architectural design.