Death's End (Remembrance of Earth’s Past, #3)

by Liu Cixin

Life reached an evolutionary milestone when it climbed onto land from the ocean, but those first fish that climbed onto land ceased to be fish. Similarly, when humans truly enter space and are freed from the Earth, they cease to be human. So, to all of you I say this: When you think about heading into outer space without looking back, please reconsider. The cost you must pay is far greater than you could imagine.