In 1937, Jorge Luis Borges wrote a characteristically engimatic historical note and literary reflection on „Ramon Llull' s Thinking Machine.“ It was a time in history when the idea of thinking machines to support human learning became ever more prominent. The latest generation of these machines was conceived in laboratories all over the world, their development still continuing today. At that time, Borges is looking back some 650 years at Ramon Llull‘s great arts which include an ars inveniendi and inspired rational speculation ever since. This is one of five essays that looks through the lens of Borges at contemporary learning machines. It focuses on Llull‘s idea of mechanical combinatorics as an instrument of cognition, and Borges’s paradoxical conclusion that an unsound method turns out to be a productive tool for creativity and especially a tool for forging poetic metaphors. The essay considers parallels to modern technologies of artificial intelligence, neural networks, and generative creativity, and also reflects on the role of humans and machines in the process of thinking and the nature of meaning. In the gap between design and realization and from technical failure Borges shows that creativity cannot arise out of emptiness; it is not creation ex nihilo, it is choice from a multitude of possibilities.