John I was said to be a model of feudal prince: brave, adventurous; excelling in every form of active exercise, fond of display, and generous in temper. He was considered one of the most gifted princes of his time. This made him very popular in Middle Ages poetry and literature. Even today there exists an ode to him, so well known that it was a potential candidate to be the North Brabant anthem. John I delighted in tournaments and was always eager to take part in jousts. He was also famous for his many illegitimate children.
