"There is no need for me to introduce, much less recommend, Mr Isaiah Berlin to you. His learning is notorious, and joined with it is a brilliant turn of dialectic which has dazzled many audiences. Listening to him you may think that you are in the presence of one of the great intellectual virtuosos of our time: a Paganini of ideas. And you would not be wrong. But do not be deceived. The art of which he is a master is not an easy art."