Mathematics and Physics:

"it's the beauty of mathematics, as opposed to physics, that it's forever. I published my selected papers recently in one volume, and I found out that when you publish your selected papers most of the physics is ephemeral, that you don't want to publish stuff that was written 10 or 20 years earlier, but the mathematics is permanent. So essentially everything I've ever published in mathematics is there, whereas only about a quarter of what I published on physics was worth preserving."

Freeman Dyson