Gregory Petsko — American Scientist
Gregory A. Petsko is an American biochemist and member of the National Academy of Sciences. He has an endowed professorship at Weill Cornell Medical College, is an adjunct professor at Cornell University, and is a professor emeritus at Brandeis University... (wikipedia)
For thousands of years, long before there was such a thing as a science of chemistry, people were fascinated by plants, because they knew that plants contained substances that could affect people. Coffee will keep you awake. Tobacco contains something that will calm your nerves. Foxglove contains an extract that'll affect your heart.
