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I use ‘Earth’ for the modern, Copernican conception of the Earth as a rotating terraqueous globe, which is one of the planets; ‘earth’ for the pre-Copernican conception of the world we inhabit, being made up of the element earth, which is stationary at the centre of the universe.

An immediate consequence, therefore, which is the subject of Chapter 4, was a radical transformation in the understanding of how the Earth is constructed: the emergence of the concept of the terraqueous globe.

Only later, in 1629, was a satisfactory technical term invented to identify unambiguously this new entity: it was called ‘the terraqueous globe’.

It is evident from the text of On the Revolutions that the concept of the terraqueous globe was of fundamental importance to him; this was surely the last building block in the construction of the new theory.

In the wake of Columbus’s discovery of America a silent revolution occurred, the invention of what we now call ‘the terraqueous globe’.