The fourth of Isaiah Berlin's famous 1965 Mellon Lectures In March–April 1965 Isaiah Berlin delivered his most famous series of public lectures, the A. W. Mellon Lectures (sponsored by the Bollingen Foundation), at the National Gallery of Art, Washington, DC. The lectures were entitled 'Some Sources of Romanticism', and transcripts were published posthumously as 'The Roots of Romanticism', edited by Henry Hardy (London, 1999: Chatto and Windus; Princeton, 1999: Princeton University Press). A second edition was published by Princeton in 2013, with a new foreword by John Gray and an appendix containing contemporary letters about the lectures.