Quoted in Fade to Black: Christoffer Boe http://digitalcontentproducer.com/mag/video_fade_black_31/, interview with Darroch Greer, Millimeter (September 1, 2004)
“If you really want to contribute to our theoretical understanding of physical laws — and it is an exciting experience if you succeed! — there are many things you need to know. First of all, be serious about it!”
How to become a good theoretical physicist http://www.phys.uu.nl/~thooft/theorist.html
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Gerardus 't Hooft 8
Dutch theoretical physicist and Nobel Prize winner 1946Related quotes

“If at first you don't succeed, you're about average.”
Fat Albert and the Cosby Kids.
Why Is It So?, episode 1 (1963) http://www.abc.net.au/science/features/whyisitso/, Australian ABC Television show
Context: Whatever work you undertake to do in your lifetime, it is very important that first you have a passion for it — you know, get excited about it — and second, that you have fun with it. That's important. Otherwise, you see, your work becomes nothing but an idle chore. Then, you hate the life you live.

“If at first you don't succeed, destroy all evidence that you tried.”
“If at first you don’t succeed, destroy all evidence that you tried.” - Chloe Traeger”
Source: Head Over Heels