Manuscript fair copy of an unpublished treatise on the Eucharist by Nicolás de Olea, written in a cursive humanistic script. The existence of this manuscript was known to J.T. Medina, who notes in the entry for Olea's Summa tripartita scholasticae philosophiae, "Se atribuyen a Olea un Tractatus de admirabili Eucharistiae Sacramenti, 1676, manuscrito en 4o., y otros que enumera Torres Saldamando."