The plates of the present work are impressed by the agency of Light alone, without any aid from the artist's pencil.
Brief Historical Sketch of the Invention of the Art William Henry Fox Talbot, 1846
Light acts chemically upon bodies. It is absorbed, it combines with them, and communicates new properties. Such, in a few words, is the principle of the discovery.
Description of Heliography (with notes by Louis Daguerre) Louis Jacques Mandé Daguerre, Nicéphore Niépce, 1829
The examples that I have the honor of presenting are the first results of my extensive research on the manner of fixing the image of objects by the action of light.
Heliography: Designs and Engravings Nicéphore Niépce, 1827
Keilmesser Stone Tool 30000BCE
Numerous experiments made by the author prove that light cannot fall upon a body without leaving traces of decomposition on the surface upon which it impinges.
Modifications and Improvements to N. Niepce Process of Heliography Louis Jacques Mandé Daguerre, 1829
