History
Psoralens have been known since ancient Egypt but have only been available in a chemically synthesized form since the 1970s.
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Famous quotes containing the word history:
“Classes struggle, some classes triumph, others are eliminated. Such is history; such is the history of civilization for thousands of years.”
—Mao Zedong (1893–1976)
“When the history of guilt is written, parents who refuse their children money will be right up there in the Top Ten.”
—Erma Brombeck (20th century)
“The history of the world is none other than the progress of the consciousness of freedom.”
—Georg Wilhelm Friedrich Hegel (1770–1831)