This article analyses an unpublished manuscript (here referred to as the Cuaderno Español) discovered in a private collection in Madrid, which contains eight folios of calligraphy by the hand of Baldericus van Horicke (†1643), a noted writing master active primarily at the court of the Archdukes of Austria in Brussels. A detailed paleographical study of the new manuscript enhances our knowledge of this exceptional virtuoso of the pen, who practiced at the height of the golden age of the writing arts in Europe. Additionally, such an analysis demonstrates how these calligraphic materials were used to teach the art of writing from the seventeenth century onwards.