Besides his significant studies on the cultural and artistic roots of the Basque country, Oteiza expressed his main aesthetic concerns and his ideological commitment in numerous texts and, in 1959, he decided to abandon sculpture altogether to devote himself entirely to art theory and the study of Basque cultural identity. From then on, his work included collaborations in fields as diverse as architecture, poetry and cinema. Like Desocupación no cúbica del espacio (Non-cubic emptying of space), Oteiza’s Caja metafísica por conjunción de dos triedros (Metaphysical box by the conjunction of two trihedra) is also part of the series dedicated to Construcciones vacías (Empty constructions) and Cajas metafísicas (Metaphysical boxes). It is based on complex combinations of stepped planes and internal and external spatial volumes. Despite its affinity with Neo-Plasticist and Suprematist practices, the procedures used in this sculpture follow a constant trend in the artist’s trajectory: his determination to preserve the vital content of his works in the face of pure logistics. In opposition to the analytic rigidity of mathematics, the Basque sculptor favours biology and physics, two sciences anchored in reality. OF MY EMPTYING OF SPACE creation of voids in empty spaces in sculpture as experimental object spatial emptying of the cube of the sphere and the cylinder while embracing Cézanne emptying of the polyhedron emptying of the city in architecture and urbanism empty the city to see the sky in the cinema concavity and holes in sports places outside the world in football displace defences open holes to escape. Jorge Oteiza, n/d