“Half genius and half buffoon,” Freeman Dyson ... wrote. ... [Richard] Feynman struck him as uproariously American—unbuttoned and burning with physical energy. It took him a while to realize how obsessively his new friend was tunneling into the very bedrock of modern science.

According to the theory of aerodynamics, as may be readily demonstrated through wind tunnel experiments, the bumblebee is unable to fly. This is because the size, weight and shape of his body in relation to the total wingspread make flying impossible. But the bumblebee, being ignorant of these scientific truths, goes ahead and flies anyway—and makes a little honey every day.

For terrestrial vertebrates, the climate in the usual meteorological sense of the term would appear to be a reasonable approximation of the conditions of temperature, humidity, radiation, and air movement in which terrestrial vertebrates live. But, in fact, it would be difficult to find any other lay assumption about ecology and natural history which has less general validity. … Most vertebrates are much smaller than man and his domestic animals, and the universe of these small creatures is one of cracks and crevices, holes in logs, dense underbrush, tunnels, and nests—a world where distances are measured in yards rather than miles and where the difference between sunshine and shadow may be the difference between life and death. Actually, climate in the usual sense of the term is little more than a crude index to the physical conditions in which most terrestrial animals live.

In the discussion of the. energies involved in the deformation of nuclei, the concept of surface tension of nuclear matter has been used and its value had been estimated from simple considerations regarding nuclear forces. It must be remembered, however, that the surface tension of a charged droplet is diminished by its charge, and a rough estimate shows that the surface tension of nuclei, decreasing with increasing nuclear charge, may become zero for atomic numbers of the order of 100. It seems therefore possible that the uranium nucleus has only small stability of form, and may, after neutron capture, divide itself into two nuclei of roughly equal size (the precise ratio of sizes depending on liner structural features and perhaps partly on chance). These two nuclei will repel each other and should gain a total kinetic energy of c. 200 Mev., as calculated from nuclear radius and charge. This amount of energy may actually be expected to be available from the difference in packing fraction between uranium and the elements in the middle of the periodic system. The whole 'fission' process can thus be described in an essentially classical way, without having to consider quantum-mechanical 'tunnel effects', which would actually be extremely small, on account of the large masses involved.
[Co-author with Otto Robert Frisch]

It is a strange feeling which comes over one as he stands in the centre of the tunnel, and knows that a mighty river is rolling on over his head, and that great ships with their thousands of tons burthen, sail over him. ... There is no single work of Art in London (with the exception of St. Paul's Cathedral) which excites so much curiosity and admiration among foreigners as the Tunnel. Great buildings are common to all parts of Europe, but the world has not such another Tunnel as this. There is something grand in the idea of walking under a broad river—making a pathway dry and secure beneath ships and navies!
[About visiting Brunel's Thames Tunnel, the first in the world under a navigable waterway.]

It’s like seeing a light at the end of the tunnel and the tunnel has leaves on it.
About rain forest destruction and species extinction.

Just as the spectroscope opened up a new astronomy by enabling the astronomer to determine some of the constituents of which distant stars are composed, so the seismograph, recording the unfelt motion of distant earthquakes, enables us to see into the earth and determine its nature with as great a certainty, up to a certain point, as if we could drive a tunnel through it and take samples of the matter passed through.

No steam or gas ever drives anything until it is confined. No Niagara is ever turned into light and power until it is tunneled. No life ever grows until it is focused, dedicated, disciplined.

Our abiding belief is that just as the workmen in the tunnel of St. Gothard, working from either end, met at last to shake hands in the very central root of the mountain, so students of nature and students of Christianity will yet join hands in the unity of reason and faith, in the heart of their deepest mysteries.

The bomb took forty-five seconds to drop thirty thousand feet to its detonation point, our three parachute gauges drifting down above. For half that time we were diving away in a two-g turn. Before we leveled off and flew directly away, we saw the calibration pulses that indicated our equipment was working well. Suddenly a bright flash lit the compartment, the light from the explosion reflecting off the clouds in front of us and back through the tunnel. The pressure pulse registered its N-shaped wave on our screen, and then a second wave recorded the reflection of the pulse from the ground. A few moments later two sharp shocks slammed the plane.

The Earthworm plows the whole world with his tunnels, drains and aerates the earth… If you ever buy any land, be sure it has plenty of Earthworms toiling and moiling all day so that you can sit down and relax. (1949)

The essence of engineering consists not so much in the mere construction of the spectacular layouts or developments, but in the invention required—the analysis of the problem, the design, the solution by the mind which directs it all.

We have elves here, and they help me. … While I’m digging in the tunnel, the elves will often come to me with solutions to my problem.