The original version of this composition was composed in 2013 for violin and violoncello following a suggestion by the cellist Sol Gabetta. At the beginning of 2014, I spent some time at a house of meditation in an isolated location on the Baltic where I found inspiration for the name of the work. In veneration of Saint Theresa of Avila, the piece is entitled Castillo Interior. This title refers to her book Moradas del Castillo Interior [“Dwellings of the Interior Castle”] written in 1577, considered as the magnum opus of the great mystic. In this version, it now also finds its way into the piano repertoire.