“I am thrilled to be alive at time when humanity is pushing against the limits of understanding. Even better, we may eventually discover that there are no limits.”

Terry Gilliam's flying circus (2006)
Context: I am quite bored nowadays. I don't know if it's age and the fact that I have seen so many things and am less surprised, or whether the problem is truly the content. But things have been repeating themselves for 30-40 years already. It seems to me that there is no desire to push the envelope or even to peek there. People are afraid. In the 1960s and 1970s we pushed the limits farther. More attention was paid to what was going on around.
Television and the media are everywhere and they are taking over so powerfully. They don't shut up for a second. So you are unable to think. It is very difficult to think independently when you are surrounded by all that noise. What I most aspire to is to be alone. Not lonely, but alone. To stop all this noise. That is what I do when I go to Umbria. There is no television there, no telephone.
The situation is especially serious with television. The money is dispersed among hundreds of stations so that no money is left for good things. In our time there was far greater depth. Not everything is artificial and as cheap as possible. Everyone gossips on television; it's all so trivial and it's impossible to hear anything.

The Evolution of Physics (1938) (co-written with Leopold Infeld) <!-- later published by Simon & Schuster (1967) -->
1930s
Context: Physical concepts are free creations of the human mind, and are not, however it may seem, uniquely determined by the external world. In our endeavor to understand reality we are somewhat like a man trying to understand the mechanism of a closed watch. He sees the face and the moving hands, even hears its ticking, but he has no way of opening the case. If he is ingenious he may form some picture of a mechanism which could be responsible for all the things he observes, but he may never be quite sure his picture is the only one which could explain his observations. He will never be able to compare his picture with the real mechanism and he cannot even imagine the possibility or the meaning of such a comparison. But he certainly believes that, as his knowledge increases, his picture of reality will become simpler and simpler and will explain a wider and wider range of his sensuous impressions. He may also believe in the existence of the ideal limit of knowledge and that it is approached by the human mind. He may call this ideal limit the objective truth.

His Nobel lecture, "How I Discovered Phase Contrast" (11December 1953) http://nobelprize.org/nobel_prizes/physics/laureates/1953/zernike-lecture.html

Source: The Time Axis (1949), Ch. 14 : Vega-Born

2016, State of the Union address (January 2016)

Source: 1980s, Laws of Media: The New Science (with Eric McLuhan) (1988), p. 109