“ In classless society the struggle between the new and the old and between truth and falsehood will never end. In the fields of the struggle for production and scientific experiment, mankind makes constant progress and nature undergoes constant change, they never remain at the same level. Therefore, man has constantly to sum up experience and go on discovering, inventing, creating and advancing. ”
 Mao Zedong, Quotations from Chairman Mao Tse-tung (1964). copy citation