A previously unpublished work by Polo entitled "Glosas a Nietzsche" has been published. In this volume of the "Complete Works of Leonardo Polo" we reproduce two courses he gave at the Universidad Panamericana in Mexico City during the summers of 1993 and 1994. They dealt with two of Nietzsche's works: "Thus Spoke Zarathustra" and "Ecce homo" respectively. They were recorded and the tapes were transcribed to make the text available. Dr. Ricardo Yepes, who died prematurely, collected both texts and wrote a preface, leaving this book prepared in the archive of Polo's work. When Polo wrote, years later, his book "Nietzsche as a thinker of dualities" he took up some of the ideas presented here, but he left these courses unpublished and wrote a new text. Now we make them public in order to complete our knowledge of Polo's thought on Nietzsche, an author of remarkable actuality today.