A Reith Lecture is a lecture in a series of annual radio lectures given by leading figures of the day, commissioned by the BBC and broadcast on BBC Radio 4. They were begun in 1948, in honour of the first Director-General of the BBC, John Reith.
The 2007 Lectures are given by one of the world's foremost economists, Professor Jeffrey Sachs, who explores the challenges faced by living in crowded world and the increasing disparity between the rich and the poor.
A billion people on this planet still have to survive on less than a dollar a day.
You can listen to the lectures here:
http://www.bbc.co.uk/radio4/reith2007/