# Clausius regarding energy

Clausius somewhere wrote (in German): The energy of the world is constant.'' This is a well known quotation.

What is the source, publication, the rest of the paper?

[Obviously he was summarizing the conservation of energy principle of Mayer by making a trivial inference. Mayer in turn had actually done the water dropping experiment Carnot suggested as a definition and used the mechanical heat equivalent this implied. As far as that energy is conserved but having no idea how energy connects to heat, or proof, that was Leibniz (in his Dynamics). Mayer used the Leibniz terminology. Clausius introduced the word energy later.]