Rembrandt here portrays himself in Renaissance attire, taking inspiration from two sixteenth-century works, Raphael's Portrait of Baldassare Castiglione, now in the Musée du Louvre, Paris, and Titian's so-called Portrait of Ariosto, now in the National Gallery, London. In Rembrandt's day both these paintings were owned by an Amsterdam collector, Alfonso Lopez, and in 1639, the same year as this etching, Rembrandt made a sketch after the painting by Raphael (the sketch is now in the Albertina, Vienna).
By following the example of Raphael, Rembrandt probably wanted to be seen as his student and artistic equal. Rembrandt depicts himself fictionally, in the nostalgic garb of his Renaissance heroes - not just those from Italy, but with echoes of northern European self-portraits by artists such as Albrecht Dürer and Lucas van Leyden. He took this approach several times in the 1630s, and part of his intention was presumably to produce an image that was a worthy emulation and even improvement on its artistic ancestors, especially those in Lopez's collection that were widely known in Amsterdam.
Rembrandt's style is here rather detailed, and he brilliantly evokes the textures of his velvet cap and his hair, which to judge from other self-portraits of the period he has here lengthened - it was normally trimmed at the level of his ear.