Peter Paul Rubens

Most great painters stayed in the studio. Rubens spent a good part of his career as a working diplomat, and the two jobs fed each other. He was fluent in several languages, moved easily among princes, and ran the busiest painting workshop in Europe out of Antwerp, in what were then the Spanish Netherlands. Kings trusted him with more than portraits.

The clearest example came in 1629. Spain and England had been at war for years, and Philip IV of Spain sent Rubens to London in the guise of a visiting artist, a cover that let him be received at court without alarm while he quietly pressed Spain's case. Over about nine months he worked on King Charles I, a passionate art collector, arguing the case for peace between the two crowns and painting for him at the same time. One of the pictures he made there, an allegory of Peace and War, was itself part of the argument, showing the good things peace brings and the ruin that war carries off.

It worked. A treaty between England and Spain was signed in 1630, and before Rubens left, Charles knighted him. Philip IV would later do the same, so he ended up a knight of both kingdoms he had helped reconcile. He kept painting at an enormous rate to the end, much of it done with assistants blocking in his designs, and in his last decade he bought a country house south of Antwerp, the Chateau de Steen, whose fields and wet skies fill the landscapes he made purely for himself.