Why choose great rivers? Because they are essential links of the earth system and indispensable homeland of the mankind. But why do they need dialogue? Because every great river is unique. Integration of their uniqueness constitutes diversity, and the world is based upon harmonious coexistence of diversity. Uniqueness is already there, but harmonious coexistence and mutual complement needs dialogue. Wuhan takes this opportunity to call for dialogue. (By Mr. Yin Hongfu, stratigraphic paleontologist and academician of Chinese Academy of Sciences)