Frederick the Great, who ruled Prussia from 1740 to 1786, was that rare entity, a philosopher-king. Even before he came to the throne he not only sought out philosophers, corresponding with Voltaire, perhaps 18th-century Europe’s foremost man of letters, but also made his own contribution by publishing many philosophical essays, some of which are presented here in a highly readable translation.

In the 18th century, ‘philosophy’ was not just an academic subject but denoted informed discussion of intellectual topics as well. Writing in The Spectator in 1711, Joseph Addison declared, ‘I shall be ambitious to have it said of me, that I have brought Philosophy out of Closets and Libraries, Schools and Colleges, to dwell in Clubs and Assemblies, at Tea-Tables and in Coffee-Houses.’ Frederick shared this purpose. His essays do not address the mind–body problem or the logical structure of propositions. Rather, they deal with legislation, education and, especially, government and politics, matters about which he could fairly claim to know something.

It was not just his intellectual interests that made Frederick an exceptional king. There had been learned monarchs before: King James I of England, Queen Christina of Sweden. By publishing his essays, Frederick descended from his throne and joined the growing public sphere created by newspapers and journals, of which