Here are a couple of examples:
I recognize that many physicists are smarter than I am–most of them theoretical physicists. A lot of smart people have gone into theoretical physics, therefore the field is extremely competitive. I console myself with the thought that although they may be smarter and may be deeper thinkers than I am, I have broader interests than they have.
— Linus Pauling
If I have seen further than others, it is by standing upon the shoulders of giants.
— Isaac Newton
The most important fundamental laws and facts of physical science have all been discovered, and these are now so firmly established that the possibility of their ever being supplemented in consequence of new discoveries is exceedingly remote.
— Albert Abraham Michelson (in 1903)
Lots more. Enjoy.