The final program focused on the concepts of positive and negative liberty introduced in the 1950s by Isaiah Berlin. Curtis briefly explained how negative liberty could be defined as freedom from coercion and positive liberty as the opportunity to strive to fulfill one's potential. Tony Blair had read Berlin's essays on the topic and wrote to him in the late 1990s, arguing that positive and negative liberty could be mutually compatible. He never received a reply, as Berlin was on his death bed.