Hermann von Helmholtz

The older view of the nature of heat was that it is a substance, very fine and imponderable indeed, but indestructible, and unchangeable in quantity, which is an essential fundamental property of all matter.

I then endeavoured to show that it is more especially in the thorough conformity with law which natural phenomena and natural products exhibit, and in the comparative ease with which laws can be stated, that this difference exists.

When I start getting embroiled in heated debates and feeling stressed, I just turn everything off and disconnect from the world. I simply tell my colleagues and friends that I am not well and need to cancel all meetings for a day or more. I take it easy - go for a long hike, take a vacation somewhere, or just stay at home and read.