Light can be considered from many points of view. Light is essential for the development of life on Earth, has determined animal and plant evolution, and has also a role in many aspects of culture and art.
«The time has come to close the book on infectious diseases. We have basically wiped out infection in the United States». These optimistic words were addressed to the United Nations General Assembly in 1966 by William H. Stewart, the Surgeon General of the United States (leading spokesperson on matters of public health).