Philip Cohen gave the 7th annual Lehninger Lecture at Johns Hopkins University, Baltimore on March 12th 2002. Held in honour of one of the world's most famous bioenergeticists, Albert Lehninger (1917-1986) is most widely known for writing the first really comprehensive textbook of biochemistry that was the standard volume for most of the world's undergraduate biochemistry courses in the 1970s and early 1980s. The lecture was attended by Albert's daughter who flew down from Boston for the day.