 These two closely related propositions – that absolute certainty is an impossible ideal (Berlin once wrote that, if his work displayed any ‘single tendency’, it was a ‘distrust of all claims to the possession of incorrigible knowledge about issues of fact or principle in any sphere of human behaviour’: 1978a, x), and that not everything can or should be reduced or related to a single ideal, model, theory or standard – might be considered the centrepieces of Berlin’s philosophy. They are central to his view of language and knowledge; they are equally important to his ethics and his philosophy of the humanities. Also central to these different facets of his thought was Berlin’s emphasis on the importance, and indeed priority, of particular things as objects of knowledge and of individual people as moral subjects.