What fundamental concept did William Henry Fox Talbot’s Calotype system introduce to chemical photography?

Answer

The negative-positive process allowing mass reproduction.

Talbot’s Calotype used sensitized paper to create a translucent negative image, which could then be used to make a virtually unlimited number of positive prints, forming the bedrock of modern photographic reproduction.

What fundamental concept did William Henry Fox Talbot’s Calotype system introduce to chemical photography?
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