The romantic and enigmatic character of this picture has inspired many theories about its subject, meaning, history, and even its attribution to Rembrandt.
Several portrait identifications have been proposed, including an ancestor of the Polish Oginski family, which owned the painting in the eighteenth century, and the Polish Socinian theologian Jonasz Szlichtyng. The rider’s costume, his weapons, and the breed of his horse have also been claimed as Polish. But if The Polish Rider is a portrait, it certainly breaks with tradition. Equestrian portraits are not common in seventeenth-century Dutch art, and furthermore, in the traditional equestrian portrait the rider is fashionably dressed and his mount is spirited and well-bred.
The painting may instead portray a character from history or literature, and many possibilities have been proposed. Candidates range from the Prodigal Son to Gysbrech van Amstel, a hero of Dutch medieval history, and from the Old Testament David to the Mongolian warrior Tamerlane.
It is possible that Rembrandt intended simply to represent a foreign soldier, a theme popular in his time in European art, especially in prints. Nevertheless, Rembrandt’s intentions in The Polish Rider seem clearly to transcend a simple expression of delight in the exotic. The painting has also been described as a latter-day Miles Christianus (Soldier of Christ), an apotheosis of the mounted soldiers who were still defending Eastern Europe against the Turks in the seventeenth century. Many have felt that the youthful rider faces unknown dangers in the strange and somber landscape, with its mountainous rocks crowned by a mysterious building, its dark water, and the distant flare of a fire.
Source: Art in The Frick Collection: Paintings, Sculpture, Decorative Arts, New York: Harry N. Abrams, 1996.