The scientists quest

"[...] how difficult it is to try to wrest precious, fundamental secrets from nature. That quest can be compared to climbing a mountain, and when reaching the peak, seeing another higher mountain that tempts us to ascend to even greater heights. And when we do reach the higher peak, we discover as we look across the valley yet another peak that calls. In the end, it is the wonderful experience of scaling the mountain — of attempting to understand the secrets of nature — that motivates us as scientists. There is of course the additional thrill, upon reaching the top of a mountain, to ram in the flagpole announcing one's victory. But that is only a momentary emotion soon superseded by the new challenges presented by the higher peak on the horizon.
[...] I believe that with the ascent of each mountain — each theory, each paradigm — we reach a new truth, but that no mountain peak can ever represent the ultimate theory of nature."

John W. Moffat, "Reinventing gravity" (p. 222).

Make sure you have data first

"I have no data yet. It is a capital mistake to theorize before one has data. Insensibly, one begins to twist facts to suit theories instead of theories to suit facts."

Sir Arthur Conan Doyle (Sherlock Holmes), as quoted by John W. Moffat in "Reinventing gravity" (p. 156).

This statement means the same thing as that one from Feynman.