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.

The popular mythology of creative genius depends on beloved stereotypes of the artist in youth and old age: the misunderstood upstart who forces us to see the world afresh; and the revered sage who shows us depths of insight attainable only through a lifetime of hard-won experience.