A selection of Berlin’s letters has been published in four volumes. Since publication, further letters have come to light, and some of these are available on this site in PDF form, volume by volume:
In an additional selection of letters from the period of the last volume, ‘More Explaining’, Berlin responds to enquiries about his own ideas.
There is also an interesting cache of letters written to Berlin by Solomon Rachmilevich between 1935 and his death in 1953.
Further letters will be posted in due course.