This edition, the first of DUAL Collection, gathers a selection of four articles previously published in 'Aldo van Eyck, Writings', edited by Vincent Ligtelijn and Francis Strauven, in 2008. The articles 'Like that other gift', 'R.R.P (Rats, Posts and other Pests' 'Symmetry from the bright side' and 'The Circle and the Center' are again published by Calmo along with their Spanish translation and an essential introduction of the context by Alejandro Campos Uribe.