Adam Phillips writes:

The letters cover the period when he switched from teaching philosophy to teaching the history of ideas (a new discipline), when he wrote the lectures and essays for which he became famous – The Hedgehog and the Fox, ‘A Remarkable Decade’ (the Northcliffe Lectures on Russia in the 19th century), ‘Two Concepts of Liberty’ – and began to describe and redescribe the conflict between conformity and originality, consensus and individualism, assimilation and having something to vent, that obsessed him. His ‘usual tendency to reduce politics to personal issues’ meant in practice what he called liking ‘the history of ideas, and in particular . . . the personalities associated with ideas’. His writing in the history of ideas wasn’t in the least confessional – though the letters, even more than the biography, make it clear, perhaps inevitably, just how much his portraiture was self-portraiture – but it was a strange mixture of hero and anti-hero worship, of theories described as if they were characters.

(LRB 23 July 2009)

Chatto | hardback 844 pp. |ISBN: 9780701178895