By the end of 1974, Mars, Venus, Mercury and Jupiter had all been visited by spacecraft. For the first time scientists saw in sharp detail the continents, mountains, valleys and volcanoes of other worlds. Tonight's programme shows how these geological features give clues to the way the planets evolved; how they have helped scientists in their attempt to reach back 5,000 million years to understand the formation of the solar system itself.

This is a report by Horizon on Transcendental Meditation, or TM, brought to the West by the Maharishi Mahesh Yogi.

Horizon presents a portrait of the renowned economist John Maynard Keynes, Cambridge Don, and Bloomsbury intellectual.

Horizon examines a hypothesis that life itself manipulates the planet to enhance it's own survival.