“But eyes are blind. You have to look with the heart”. IBA Berlin 1979 – 1987, the drawing as tool to read and disclose

"It is only with the heart that one can see rightly; what is essential is invisible to the eye.” (Costanzo, 1991, p.14) On the occasion of his direction of the Berlin International Bauausstellung (IBA 1979-1987) the German architect Josef Paul Kleihues referred to the fable of Antoine de Saint - Exupéry to encourage architects to awaken the values of ingenuity and imagination. He emphasized the Imago, as a point of reference and stable values at the base of human consciousness. The problem is based on the dialectic between tradition and modernity, the field of experimentation on which he himself elaborates the concept of "critical reconstruction". According to the architect, the rediscovery of the laws of the historic city is a decisive instrument for Berliners to recognize themselves in it. Another important concept which Kleihues placed at the base of his guidelines is the "poetic rationalism" presented during the Triennale di Milano exhibition entitled "The cities of the world of 1988 and the future of the metropolis". On this occasion, he maintained that "the possibility of a new rationalism exists only when the deterministic tendency is questioned by poetry". (Kleihues, 1989, p.57) Through this “poetic rationalism”, he criticizes the excessive bureaucracy that conditions and limits the creative process. One of the most interesting areas of the Berlin International Bauausstellung is the Südliche Friedrichstad. It is interesting to take into account the rules imposed by Josef Paul Kleihues about the permanence of the existing layout and the reconstruction of the continuity of the facades along the plot perimeter and to see how the architects Aldo Rossi and Rem Koolhaas stand about these principles. The proposed study investigates their interpretation of the concept of "poetic rationalism" through drawing, considered by the author as a fundamental interpretative, creative and cognitive activity.