A masterwork of tension and balance, Chillida's *Bikoiztasun (Duality)* employs the rich, velvety depths of aquatint to explore the interplay between opposing forces — light and shadow, presence and void. Printed on warm Eskulan gray paper, the composition's bold, angular forms emerge with a tactile weight that is distinctly the artist's own, evoking his lifelong fascination with space and matter. The full margins lend the work a contemplative stillness, framing Chillida's abstract language as a meditation on the fundamental duality that underlies all existence.