Leopoldo de' Medici in Polish costume

The child in the fur-trimmed coat and tall plumed cap is Leopoldo de' Medici, painted around 1622 when he was about five, dressed in the Polish fashion that European courts liked to borrow for masques and portraits. As a younger son he was never going to rule, and that freedom pointed him toward books and curiosity instead. He was eventually made a cardinal, though the passion that lasted was inquiry. In 1657 he and his brother the grand duke founded an academy of experiment in Florence, whose members tested claims about heat, cold and air with instruments built to settle the question. The plumed boy here grew up to sign his letters as a cardinal and spend his evenings among lenses and thermometers.