“There's different types of knowledge, and this is where I believe the confusion lies. There's experimental or observational science as we call it. That's using the scientific method: observation, measurement, experiment, testing. That's what produces our technology: computers, spacecraft, jet planes, smoke detectors, looking at DNA, antibiotics, medicines and vaccines. You see, all scientists, whether Creationist or Evolutionist, actually have the same observational or experimental science. It doesn't matter if you're a Creationist or an Evolutionist: you can be a great scientist… But I want us to also understand that molecules-to-man evolution belief has nothing to do with developing technology.”

“The Environment and Disease: Association or Causation?,” Proceedings of the Royal Society of Medicine, 58 (1965), 295-300

Letter to Wilhelm Fliess, Feb. 1, 1900. The Complete Letters of Sigmund Freud to Wilhelm Fliess 1887-1904 (1985).
Ich bin nämlich gar kein Mann der Wissenschaft, kein Beobachter, kein Experimentator, kein Denker. Ich bin nichts als ein Conquistadorentemperament, ein Abenteurer, wenn Du es übersetzt willst, mit der Neugierde, der Kühnheit und der Zähigkeit eines solchen.
1900s

Knowing Yourself: The True in the False (1996)

No. 15
On the Interpretation of Nature (1753)
Context: There are three principal means of acquiring knowledge available to us: observation of nature, reflection, and experimentation. Observation collects facts; reflection combines them; experimentation verifies the result of that combination. Our observation of nature must be diligent, our reflection profound, and our experiments exact. We rarely see these three means combined; and for this reason, creative geniuses are not common.

"Bill Nye Debates Ken Ham" (February 4, 2014)

you don't see electrons, gravity, or black holes either
Source: Wonderful Life (1989), p. 279

That is the principle of science. If there is an exception to any rule, and if it can be proved by observation, that rule is wrong.
lecture I: "The Uncertainty of Science"
The Meaning of It All (1999)

1962, Rice University speech
Context: The growth of our science and education will be enriched by new knowledge of our universe and environment, by new techniques of learning and mapping and observation, by new tools and computers for industry, medicine, the home as well as the school. Technical institutions, such as Rice, will reap the harvest of these gains. And finally, the space effort itself, while still in its infancy, has already created a great number of new companies, and tens of thousands of new jobs. Space and related industries are generating new demands in investment and skilled personnel, and this city and this state, and this region, will share greatly in this growth.

Source: Course of Experimental Philosophy, 1745, p. v: Preface
Context: All the knowledge we have of nature depends upon facts; for without observations and experiments our natural philosophy would only be a science of terms and an unintelligible jargon. But then we must call in Geometry and Arithmetics, to our Assistance, unless we are willing to content ourselves with natural History and conjectural Philosophy. For, as many causes concur in the production of compound effects, we are liable to mistake the predominant cause, unless we can measure the quantity and the effect produced, compare them with, and distinguish them from, each other, to find out the adequate cause of each single effect, and what must be the result of their joint action.