'I was exhausted at the end, & yet I am sure that if ever I saw & 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 ninetheenth centuries.

This is also the mine from which Berlin quarried many of his well-known later publications, including 'Two Concepts of Liberty', 'Historical Inevitability' and his essays on Vico and Herder; the continuities and changes that appear when the earlier and later versions of his ideas are compared throw new light on his thought. Written in Berlin's characteristically accessible style, the book also contains much that is not to be found elsewhere in his writings. It is a distillate of his formative early work in the history of ideas, and the longest continuous text he ever wrote.

The often problematic script left by Berlin has been edited for publication by Henry Hardy. Joshua Cherniss contributes an introduction setting the work in its context in Berlin's life and work, and a bibliography of related works by Berlin and others.