Which C.S. Lewis work contains the argument that humans should not be reduced to nature alone?

The C.S. Lewis work containing that argument is The Abolition of Man.

In this 1943 philosophical book, Lewis warns that attempts to reshape human nature through purely instrumental control could ultimately undermine the very qualities that make humans human. His argument develops from a discussion of moral education and the rejection of objective values.

Lewis’s concern is not simply that technology might become powerful. He focuses on the moral assumptions guiding human control over nature. If one generation gains the power to manipulate later generations, the controllers may gradually determine what counts as human desire, judgment, and purpose. The result, he suggests, could be the abolition of humanity in a meaningful moral sense.

The work is often read alongside Lewis’s essays on education, science, and modernity. It is separate from The Four Loves, which examines types of human affection, and from Miracles, which argues for the possibility of supernatural events.