Joan Torras, professor of the strength of materials at the School of Architecture of Barcelona (1871-1910), considered the beam of equal strength not only as a structurally extremely efficient beam, but also as beautiful because of its ability to reflect the material's strength. Torras' structures have left their special mark on Barcelona and on the work of his most illustrious students: Rafael Guastavino in the United States published similar structures, but it was Antoni Gaudi and Josep Maria Jujol who transfigured them mimetically for Barcelona's Park Guell and Tarragona's Metropol Theatre, respectively. These examples will show how an expressive gesture can thoroughly transform a "technical form" into an "artistic form", a fact that inevitably recalls the wisdom of classical Greek mimesis.