Imagine the most powerful political leader in the world decides he's not interested in politics and wars and all that and prefers to dedicate most of his time to collecting art and dabbling in science. Amazingly, it really happened: the leader in question was the Habsburg emperor Rudolf II, who presided over the Holy Roman Empire in the twilight years before central Europe drowned in the Thirty Years War.
In his very readable biography of the ruler who couldn't be bothered to rule, Peter Marshall follows the interests of his subject by dedicating only a little bit of space to the politics, and focusing on the art and the science instead. To get the politics out of the way first, many have slated Rudolf as a hopeless leader, but Marshall tends to support the view that his inaction and openness for divergent opinions (especially on religion, where he refused to support hardline Catholicism) quite possibly delayed the inescapable disaster by several decades.
Rudolf's credentials are much clearer in art and in science. His support for the most exciting astronomers of the day brought together the last and greatest naked-eye observer of the heavens, Tycho Brahe, and the best theoretician of the time, Johannes Kepler. Without Rudolf's patronage, the movement of the planets (Kepler's laws) might have remained unsolved for much longer.
Astronomers of the day still very much believed in astrology, or at least used it as a welcome source of income, so we're looking at an important junction between the medieval world views we now call superstition and the emerging modern science. Thus there are also alchemists and magi like the Briton John Dee populating the pages of this book.
In art, Rudolf supported many great artists, including Arcimboldo, who famously portrayed the emperor as a jigsaw made of vegetables. Marshall says that Rudolf often left important political figures waiting for an appointment, as he preferred to spend his time in the workshops of his artists, discussing their current work.
Of equal importance, though, was his unprecedented activity as a collector. He sent expert buyers including Jacopo Strada and his son Octavio to Italy, to buy art of what we now call the late Renaissance and bring it to Prague, the city which owes the time of its greatest glory to him.
With chapters dedicated to subject areas (magic, art, old astronomy, new astronomy) and the key figures representing them, Marshall's book is a very accessible read. Minor moans from my part include the fact that the Strada family have not been given a whole chapter as they would have deserved - I think it's fair to say that they are as important for Rudolf's circle as the visitor John Dee. I would have also wished the author to be more aware of points where the textbook history may be wrong: He uncritically refers to "Juana la loca" (Rudolf's great grand-mother in two lineages) as having been mad, and to a strained bladder as the cause of Tycho's death. In both cases, I would have liked to see alternative explanations discussed.