“Just as it is certain that one leaf is never totally the same as another, so it is certain that the concept "leaf" is formed by arbitrarily discarding these individual differences and by forgetting the distinguishing aspects. This awakens the idea that, in addition to the leaves, there exists in nature the "leaf": the original model according to which all the leaves were perhaps woven, sketched, measured, colored, curled, and painted--but by incompetent hands, so that no specimen has turned out to be a correct, trustworthy, and faithful likeness of the original model.”

German philosopher and writer

Friedrich Nietzsche was a German philosopher and writer. He began as a classical philologist, then turned to philosophy early in his academic career, and is known for a body of work that drew wide scholarly attention and lasting popular interest. In 1869 he became Professor of Classical Philology at the University of Basel, but he resigned in 1879 because of long-standing health problems. After that he lived as an independent writer, often in solitude and financial insecurity, moving between Switzerland, Italy, and southern France. He completed much of his main work in the following decade, before a neurological collapse in 1889 ended his working life.