If you are lying in a tent in the Congo jungle, you don't want to be reading about rainforest biology. You want to be in a distant world.

You can hike into the Yellowstone backcountry. You can camp in the Yellowstone backcountry. You can take food into the Yellowstone backcountry, and you're surrounded by grizzly bears. And it's - it's a very, very thrilling, peculiar situation. Every sound that you hear in the night, you wonder is this a grizzly bear coming to tear into my tent?

[Theory is] an explanation that has been confirmed to such a degree, by observation and experiment, that knowledgeable experts accept it as fact. That's what scientists mean when they talk about a theory: not a dreamy and unreliable speculation, but an explanatory statement that fits the evidence. They embrace such an explanation confidently but provisionally - taking it as their best available view of reality, at least unil some severely conflicting data or some better explanation might come along.

The swallow that hibernates underwater is a creature called yearning.

And so in 1975, the grizzly bear was put on, as I said - on the endangered species list as threatened. And new measures were taken, for instance, bear-proofing garbage, creating new regulations to - essentially to try and keep people and people's food away from the bears, let the bears adjust to eating the abundant wild food that's available in Yellowstone and allow them to be more wild, to be independent of humans as sources of foods for the good of both sides. And that has been quite successful.

Nor are we the culmination of evolution, except in the sense that there has never been another species so bizarrely ingenious that it could create both iambic pentameter and plutonium.

Results "are no good unless they answer (or can be made to seem to answer, or can be twisted and wrenched and piled into odd shapes until they hint at being somehow perhaps on the verge or answering) a question that someone might conceivably want asked."