‘I was exhausted at the end, and yet I am sure that if ever I saw and heard anyone in a true state of inspiration it was then.’ So wrote Isaiah Berlin’s secretary Lelia Brodersen to a friend in 1952, after hearing one of Berlin’s Mary Flexner Lectures at Bryn Mawr College, Pennsylvania. Political Ideas in the Romantic Age , written in preparation for these lectures, was heavily revised by Berlin afterwards, though he never brought it to final published form. But it is a work of the greatest interest, both for what Berlin says about his subject and for what it tells us about his own intellectual development. It is the only text he ever wrote in which he laid out in one connected account most of his key insights about the history of ideas in the period which he made his own - the ‘romantic age’ - the bridge between the eighteenth and nineteenth centuries. Written in Berlin’s characteristically accessible style, the book also contains much that is not to be found elsewhere in his writings. It is also the mine from which he quarried a number of his best-known later publications, including Two Concepts of Liberty , Historical Inevitability and his essays on Vico and Herder. The often problematic text left by Berlin has been edited for publication by Henry Hardy. Joshua L. Cherniss has contributed an introduction which sets the book in the context of Berlin’s life and work.